### What changes were proposed in this pull request?
There are total 15 compilation warnings about `Unicode escapes in triple quoted strings are deprecated` in Spark code now:
```
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2930: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2931: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2932: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2933: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2934: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2935: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2936: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/core/src/main/scala/org/apache/spark/util/Utils.scala:2937: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/csv/CSVExprUtils.scala:82: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/csv/CSVExprUtilsSuite.scala:32: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/csv/CSVExprUtilsSuite.scala:79: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ParserUtilsSuite.scala:97: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ParserUtilsSuite.scala:101: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/json/JsonParsingOptionsSuite.scala:76: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
[WARNING] /spark-source/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/json/JsonParsingOptionsSuite.scala:83: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
```
This pr try to fix these warnnings.
### Why are the changes needed?
Cleanup compilation warnings about `Unicode escapes in triple quoted strings are deprecated`
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Pass the Jenkins or GitHub Action
Closes#30926 from LuciferYang/SPARK-33801.
Authored-by: yangjie01 <yangjie01@baidu.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
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