[SPARK-43253][SQL] Assign a name to the error class _LEGACY_ERROR_TEMP_2017

[adityaksolves]

What changes were proposed in this pull request?

Assigned a proper name to the legacy error class _LEGACY_ERROR_TEMP_2017
in error-conditions.json. The error is now named UNRESOLVED_COLLECTION_CLS
with an improved error message and sqlState 0A000.

Why are the changes needed?

_LEGACY_ERROR_TEMP_2017 was a temporary placeholder name from the error
class migration project. This PR gives it a meaningful name that clearly
describes the error condition.

Does this PR introduce any user-facing change?

Yes, the error message has been improved from the vague "not resolved." to
"Custom collection class is not resolved. Ensure the class is accessible
and properly defined before analysis."

How was this patch tested?

Added a new test in ObjectExpressionsSuite that verifies the error class,
condition name, and parameters using checkError().

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

No.

[adityaksolves]

The Docker integration test failure (MySQLNamespaceSuite) appears to be a flaky infrastructure issue unrelated to this change. All other test suites pass. cc @MaxGekk