[SPARK-46831][INFRA][FOLLOWUP] Fix a wrong JIRA ID in MimaExcludes

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

This is a follow-up of
- #44901

### Why are the changes needed?

To fix the wrong JIRA ID information.

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

No.

### How was this patch tested?

Manual review.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #45071 from dongjoon-hyun/SPARK-46831.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

project/MimaExcludes.scala

@@ -76,7 +76,7 @@ object MimaExcludes {
 
     // SPARK-46410: Assign error classes/subclasses to JdbcUtils.classifyException
     ProblemFilters.exclude[DirectMissingMethodProblem]("org.apache.spark.sql.jdbc.JdbcDialect.classifyException"),
-    // [SPARK-464878][CORE][SQL] (false alert). Invalid rule for StringType extension.
+    // TODO(SPARK-46878): Invalid Mima report for StringType extension
     ProblemFilters.exclude[DirectMissingMethodProblem]("org.apache.spark.sql.types.StringType.this"),
     // SPARK-47011: Remove deprecated BinaryClassificationMetrics.scoreLabelsWeight
     ProblemFilters.exclude[DirectMissingMethodProblem]("org.apache.spark.mllib.evaluation.BinaryClassificationMetrics.scoreLabelsWeight")