[AURON #2431] Prune Iceberg changelog tasks by metadata predicates

[goutamadwant]

Which issue does this PR close?

Closes #2431

Rationale for this change

Iceberg changelog metadata values are constant for each changelog task. Auron currently plans every supported task in the changelog range even when a predicate on _change_type, _commit_snapshot_id, or _change_ordinal proves that a task cannot match.

What changes are included in this PR?

• Associate supported metadata-only filters with an unambiguous Iceberg changelog scan before adaptive query stages are created.
• Prune validated changelog tasks for = and IN predicates combined with AND.
• Keep OR, NOT, complex expressions, mixed data-column predicates, and ambiguous scan matches on the existing post-scan filter path.
• Preserve existing fallback validation for unsupported changelog tasks and mixed file formats.
• Add regression coverage for matching, nonmatching, conjunction, and unsupported-expression cases.

Are there any user-facing changes?

Yes. Eligible Iceberg changelog queries plan and read fewer native scan files. There are no public API or configuration changes.

How was this patch tested?

• AuronIcebergIntegrationSuite: 43 tests passed.
• Focused changelog metadata pruning regression: passed.
• ./dev/reformat --check: passed across the configured Spark 3.0-3.5 and 4.0-4.1 profiles.
• ./build/mvn -B spotless:check test-compile -pl thirdparty/auron-iceberg -am -Ppre -Pscala-2.12 -Pspark-3.5 -Piceberg-1.10.1 -DskipBuildNative -DskipTests: passed.

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

• Yes
• No

Codex was used to Review and understand the codebase