Skip reporting synthetic failures

[mhdatie]

What Does This Do

Extends TagInitializationErrors.java to also tag executionError and test exception synthetic testcases
with dd_tags[test.final_status]=skip, unconditionally. Previously, only intermediate
initializationError retries were tagged.

The tagging logic is refactored into a shared tagSkip helper that uses direct child element lookups
(instead of getElementsByTagName, which searches all descendants) and is idempotent - testcases already
carrying the property are left unchanged.

Motivation

executionError and test exception are framework-level synthetic entries that never represent a real
test result. Without this change, Test Optimization treats them as genuine failures, producing noise in
the test results dashboard. Like initializationError intermediates, they should be skipped so only
real test outcomes are surfaced.

Additional Notes

• Future PR - Rename from TagInitializationErrors.java to TagSyntheticFailures.java

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
• Avoid using close, fix, or any linking keywords when referencing an issue
  Use solves instead, and assign the PR milestone to the issue
• Update the CODEOWNERS file on source file addition, migration, or deletion
• Update public documentation with any new configuration flags or behaviors

Jira ticket: APMLP-1296

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