[SPARK-36788][SQL] Change log level of AQE for non-supported plans from warning to debug

### What changes were proposed in this pull request?

This PR suppresses the warnings for plans where AQE is not supported. Currently we show the warnings such as:

```
org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324881 DESC NULLS FIRST], true, 23
+- Scan ExistingRDD[a#324881]
```

for every plan that AQE is not supported.

### Why are the changes needed?

It's too noisy now. Below is the example of `SortSuite` run:

```
14:51:40.675 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324881 DESC NULLS FIRST], true, 23
+- Scan ExistingRDD[a#324881]
.
[info] - sorting on DayTimeIntervalType(0,1) with nullable=true, sortOrder=List('a DESC NULLS FIRST) (785 milliseconds)
14:51:41.416 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324884 ASC NULLS FIRST], true
+- Scan ExistingRDD[a#324884]
.
14:51:41.467 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324884 ASC NULLS FIRST], true, 23
+- Scan ExistingRDD[a#324884]
.
[info] - sorting on DayTimeIntervalType(0,1) with nullable=false, sortOrder=List('a ASC NULLS FIRST) (796 milliseconds)
14:51:42.210 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324887 ASC NULLS LAST], true
+- Scan ExistingRDD[a#324887]
.
14:51:42.259 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324887 ASC NULLS LAST], true, 23
+- Scan ExistingRDD[a#324887]
.
[info] - sorting on DayTimeIntervalType(0,1) with nullable=false, sortOrder=List('a ASC NULLS LAST) (797 milliseconds)
14:51:43.009 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324890 DESC NULLS LAST], true
+- Scan ExistingRDD[a#324890]
.
14:51:43.061 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324890 DESC NULLS LAST], true, 23
+- Scan ExistingRDD[a#324890]
.
[info] - sorting on DayTimeIntervalType(0,1) with nullable=false, sortOrder=List('a DESC NULLS LAST) (848 milliseconds)
14:51:43.857 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324893 DESC NULLS FIRST], true
+- Scan ExistingRDD[a#324893]
.
14:51:43.903 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324893 DESC NULLS FIRST], true, 23
+- Scan ExistingRDD[a#324893]
.
[info] - sorting on DayTimeIntervalType(0,1) with nullable=false, sortOrder=List('a DESC NULLS FIRST) (827 milliseconds)
14:51:44.682 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324896 ASC NULLS FIRST], true
+- Scan ExistingRDD[a#324896]
.
14:51:44.748 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324896 ASC NULLS FIRST], true, 23
+- Scan ExistingRDD[a#324896]
.
[info] - sorting on YearMonthIntervalType(0,1) with nullable=true, sortOrder=List('a ASC NULLS FIRST) (565 milliseconds)
14:51:45.248 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324899 ASC NULLS LAST], true
+- Scan ExistingRDD[a#324899]
.
14:51:45.312 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324899 ASC NULLS LAST], true, 23
+- Scan ExistingRDD[a#324899]
.
[info] - sorting on YearMonthIntervalType(0,1) with nullable=true, sortOrder=List('a ASC NULLS LAST) (591 milliseconds)
14:51:45.841 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: ReferenceSort [a#324902 DESC NULLS LAST], true
+- Scan ExistingRDD[a#324902]
.
14:51:45.905 WARN org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan: spark.sql.adaptive.enabled is enabled but is not supported for query: Sort [a#324902 DESC NULLS LAST], true, 23
+- Scan ExistingRDD[a#324902]
.
```

### Does this PR introduce _any_ user-facing change?

Yes, it will show less warnings to users. Note that AQE is enabled by default from Spark 3.2, see SPARK-33679

### How was this patch tested?

Manually tested via unittests.

Closes #34026 from HyukjinKwon/minor-log-level.

Authored-by: Hyukjin Kwon <gurwls223@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/InsertAdaptiveSparkPlan.scala

@@ -68,7 +68,7 @@ case class InsertAdaptiveSparkPlan(
             plan
         }
       } else {
-        logWarning(s"${SQLConf.ADAPTIVE_EXECUTION_ENABLED.key} is enabled " +
+        logDebug(s"${SQLConf.ADAPTIVE_EXECUTION_ENABLED.key} is enabled " +
           s"but is not supported for query: $plan.")
         plan
       }