[SPARK-42379][SS] Use FileSystem.exists in FileSystemBasedCheckpointFileManager.exists

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

This PR proposes to use FileSystem.exists in FileSystemBasedCheckpointFileManager.exists, which is consistent with other methods in FileSystemBasedCheckpointFileManager.

This PR also removes the test case QueryExecutionErrorsSuite.FAILED_RENAME_PATH: rename when destination path already exists because the test relies on incorrect custom file system instance with non-symmetric implementation between `FileSystemBasedCheckpointFileManager.exists` vs `FileSystem.exists`.
(See detailed explanation from #39936 (comment))

### Why are the changes needed?

Other methods in FileSystemBasedCheckpointFileManager already uses FileSystem.exists for all cases checking existence of the path.

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

No.

### How was this patch tested?

Existing tests.

Closes #39936 from HeartSaVioR/MINOR-FileSystemBasedCheckpointFileManager-calls-fs-exists-in-exists.

Authored-by: Jungtaek Lim <[email protected]>
Signed-off-by: Jungtaek Lim <[email protected]>

Author: HeartSaVioR

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/CheckpointFileManager.scala

@@ -256,12 +256,7 @@ class FileSystemBasedCheckpointFileManager(path: Path, hadoopConf: Configuration
     fs.open(path)
   }
 
-  override def exists(path: Path): Boolean =
-    try {
-      fs.getFileStatus(path) != null
-    } catch {
-      case _: FileNotFoundException => false
-    }
+  override def exists(path: Path): Boolean = fs.exists(path)
 
   override def renameTempFile(srcPath: Path, dstPath: Path, overwriteIfPossible: Boolean): Unit = {
     if (!overwriteIfPossible && fs.exists(dstPath)) {

sql/core/src/test/scala/org/apache/spark/sql/errors/QueryExecutionErrorsSuite.scala

@@ -634,37 +634,6 @@ class QueryExecutionErrorsSuite
       sqlState = "0A000")
   }
 
-  test("FAILED_RENAME_PATH: rename when destination path already exists") {
-    withTempPath { p =>
-      withSQLConf(
-        "spark.sql.streaming.checkpointFileManagerClass" ->
-          classOf[FileSystemBasedCheckpointFileManager].getName,
-        "fs.file.impl" -> classOf[FakeFileSystemAlwaysExists].getName,
-        // FileSystem caching could cause a different implementation of fs.file to be used
-        "fs.file.impl.disable.cache" -> "true") {
-        val checkpointLocation = p.getAbsolutePath
-
-        val ds = spark.readStream.format("rate").load()
-        val e = intercept[SparkConcurrentModificationException] {
-          ds.writeStream
-            .option("checkpointLocation", checkpointLocation)
-            .queryName("_")
-            .format("memory")
-            .start()
-        }
-
-        val expectedPath = p.toURI
-        checkError(
-          exception = e.getCause.asInstanceOf[SparkFileAlreadyExistsException],
-          errorClass = "FAILED_RENAME_PATH",
-          sqlState = Some("42K04"),
-          matchPVals = true,
-          parameters = Map("sourcePath" -> s"$expectedPath.+",
-            "targetPath" -> s"$expectedPath.+"))
-      }
-    }
-  }
-
   test("RENAME_SRC_PATH_NOT_FOUND: rename the file which source path does not exist") {
     withTempPath { p =>
       withSQLConf(
@@ -805,10 +774,6 @@ class FakeFileSystemSetPermission extends LocalFileSystem {
   }
 }
 
-class FakeFileSystemAlwaysExists extends DebugFilesystem {
-  override def exists(f: Path): Boolean = true
-}
-
 class FakeFileSystemNeverExists extends DebugFilesystem {
   override def exists(f: Path): Boolean = false
 }