Only supervise tests that require XML generation

[alexeagle]

Summary

• add the well-known requires-test-xml-generation tag (analogous to requires-network)
• add the ensure_xml supervisor to test action inputs only when the target carries that tag and --experimental_test_xml_missing_behavior=workaround is enabled
• document the same-spawn XML fallback behavior and cover tagged and untagged actions

This keeps the supervisor out of unrelated test action inputs, avoiding wasted input bytes and broad cache invalidation when the supervisor changes.

Testing

bazel test //src/test/java/com/google/devtools/build/lib/analysis:AnalysisTests //src/test/java/com/google/devtools/build/lib/exec:ExecTests '--test_filter=TestActionBuilderTest|StandaloneTestStrategyTest'

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

^{Reviewed by Cursor Bugbot for commit 4ccd1df. Configure here.}

[cursor]

Misleading missing-XML tag hint

Low Severity

In workaround mode, the missing-XML failure always appends a hint to add requires-test-xml-generation, even when that tag is already present. Tagged tests that still lack XML (for example on unsupported platforms where ensure_xml is omitted) get an incorrect remediation hint.

 

^{Reviewed by Cursor Bugbot for commit 4ccd1df. Configure here.}

[alexeagle]

Landing without review so I can get a production build started