[SPARK-47179][SQL] Improve error message from SparkThrowableSuite for…

… better debuggability

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

This PR proposes to improve error message from SparkThrowableSuite for better debuggability

### Why are the changes needed?

The current error message is not very actionable for developer who need regenerating the error class documentation.

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

No API change, but the error message is changed:

**Before**
```
The error class document is not up to date. Please regenerate it.
```

**After**
```
he error class document is not up to date. Please regenerate it by running `SPARK_GENERATE_GOLDEN_FILES=1 build/sbt "core/testOnly *SparkThrowableSuite -- -t \"Error classes match with document\""`
```

### How was this patch tested?

The existing CI should pass.

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

No.

Closes apache#45273 from itholic/improve_error_suite_debuggability.

Authored-by: Haejoon Lee <[email protected]>
Signed-off-by: Max Gekk <[email protected]>

core/src/test/scala/org/apache/spark/SparkThrowableSuite.scala

@@ -55,6 +55,9 @@ class SparkThrowableSuite extends SparkFunSuite {
         "core/testOnly *SparkThrowableSuite -- -t \"Error classes match with document\""
    }}}
    */
+  private val regenerateCommand = "SPARK_GENERATE_GOLDEN_FILES=1 build/sbt " +
+    "\"core/testOnly *SparkThrowableSuite -- -t \\\"Error classes match with document\\\"\""
+
   private val errorJsonFilePath = getWorkspaceFilePath(
     "common", "utils", "src", "main", "resources", "error", "error-classes.json")
 
@@ -328,7 +331,8 @@ class SparkThrowableSuite extends SparkFunSuite {
         }
       } else {
         assert(subErrorDoc.trim == errorsInDoc.trim,
-          "The error class document is not up to date. Please regenerate it.")
+          "The error class document is not up to date. " +
+            s"Please regenerate it by running `$regenerateCommand`")
       }
     })
 
@@ -351,7 +355,8 @@ class SparkThrowableSuite extends SparkFunSuite {
       }
     } else {
       assert(sqlErrorParentDoc.trim == commonErrorsInDoc.trim,
-        "The error class document is not up to date. Please regenerate it.")
+        "The error class document is not up to date. " +
+          s"Please regenerate it by running `$regenerateCommand`")
     }
 
     val orphans = orphanedGoldenFiles()
@@ -368,7 +373,8 @@ class SparkThrowableSuite extends SparkFunSuite {
       }
     } else {
       assert(orphans.isEmpty,
-        "Exist orphaned error class documents. Please regenerate it.")
+        "Exist orphaned error class documents. " +
+          s"Please regenerate it by running `$regenerateCommand`")
     }
   }