### What changes were proposed in this pull request?
If `LLL`/`qqq` is used in the datetime pattern string, and the current JDK in use has a bug for the stand-alone form (see https://bugs.openjdk.java.net/browse/JDK-8114833), throw an exception with a clear error message.
### Why are the changes needed?
to keep backward compatibility with Spark 2.4
### Does this PR introduce _any_ user-facing change?
Yes
Spark 2.4
```
scala> sql("select date_format('1990-1-1', 'LLL')").show
+---------------------------------------------+
|date_format(CAST(1990-1-1 AS TIMESTAMP), LLL)|
+---------------------------------------------+
| Jan|
+---------------------------------------------+
```
Spark 3.0 with Java 11
```
scala> sql("select date_format('1990-1-1', 'LLL')").show
+---------------------------------------------+
|date_format(CAST(1990-1-1 AS TIMESTAMP), LLL)|
+---------------------------------------------+
| Jan|
+---------------------------------------------+
```
Spark 3.0 with Java 8
```
// before this PR
+---------------------------------------------+
|date_format(CAST(1990-1-1 AS TIMESTAMP), LLL)|
+---------------------------------------------+
| 1|
+---------------------------------------------+
// after this PR
scala> sql("select date_format('1990-1-1', 'LLL')").show
org.apache.spark.SparkUpgradeException
```
### How was this patch tested?
manual test with java 8 and 11
Closes#28646 from cloud-fan/format.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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