Add --test-show-all-batch-targets to expose all targets in batched pytest

[jasonwbarnett]

Summary

• Adds a --test-show-all-batch-targets CLI flag (default: False) to the [test] subsystem
• When enabled, all target addresses in a batched pytest invocation are listed in test result summaries, workunit descriptions, and warning messages
• Default behavior is unchanged: truncated format like "path/to:tests and 3 other files"

Problem

When python_tests targets use batch_compatibility_tag, multiple targets are grouped into a single pytest invocation. The output only shows the first target plus a count (e.g. "batch of path/to:tests and 3 other files"), making it impossible to determine which specific targets are grouped together in each pytest process.

In practice, this is a real pain point when batched test runs hang or timeout in CI. A long-running batch that never finishes gives you no way to identify which specific targets in that batch are responsible. You're left guessing across potentially dozens of targets, manually bisecting to find the culprit. This flag makes that debugging tractable by showing exactly which targets are in each batch.

Solution

A new --test-show-all-batch-targets flag that, when enabled, replaces the truncated descriptions with comma-separated lists of all target addresses in three locations:

1. Test result summary line (✓ path/to:tests, path/to:tests2, path/to:tests3 succeeded)
2. Workunit/process description (Run Pytest for path/to:tests, path/to:tests2, path/to:tests3)
3. Warning messages for missing coverage/XML data

Test plan

• Verify default behavior is unchanged (flag off)
• Verify --test-show-all-batch-targets lists all addresses in test summaries
• Verify workunit descriptions show all addresses when flag is on
• Verify warning messages show all addresses when flag is on
• Test with large batch sizes to confirm readability

🤖 Generated with Claude Code

[sureshjoshi]

Thanks for the contribution. We've just branched for 2.32.x, so merging this pull request now will come out in 2.33.x, please move the release notes updates to docs/notes/2.33.x.md if that's appropriate.