DAOS-18626 test: Add per-sanitizer suite selection and JUnit reporting to run_utest.py

[knard38]

This is PR 2 of 10 in the split of DAOS-18626 (see ckochhof/dev/master/daos-18626/patch-001 for the original, unsplit commit). It extends utils/run_utest.py so the unit-test suite can be run selectively under ASan, UBSan, or TSan, and so results are reported in a form CI can consume. Nothing calls these new flags yet in this PR — that comes later in this stack.

What/why

• New --asan/--ubsan/--tsan flags select suites via new asan/tsan Suite config keys (utest.yaml); suites unsuitable under a given sanitizer (e.g. memcheck-only suites, control Go tests) opt out via asan: False/gha: False.
• New --list flag prints the suites/tests that would run, honoring all selection/filter options, without running them.
• Per-test sanitizer log capture: new-since-setup() sanitizer log files (found via the ASAN_OPTIONS/UBSAN_OPTIONS/TSAN_OPTIONS log_path= directory) are copied into each test's own log dir, tagged with a companion <logfile>.testname file for attribution.
• cmocka XML results are now written into CMOCKA_XML_FILE's directory (the Docker-mounted test-results/ volume) instead of a source-relative test_results/ directory, and only newly-appeared XML files are relabeled per test/suite.
• In GHA context, one JUnit TestCase is now written per test per suite (write_xml_result()) so result counts are accurate.
• utils/utest.yaml: tag suites with tsan: True (opt-in, TSan suites are a small subset) and asan: False/gha: False (opt-out) as appropriate for each suite.

Testing

• python3 utils/run_utest.py --asan --list, --ubsan --list, --tsan --list print the expected suite/test subsets (manually verified against utest.yaml's new tags).
• Existing (no-flag) invocation behavior is unchanged — this is a backward-compatible, additive change.
• No CI job invokes these new flags yet in this PR; they're exercised end-to-end starting with PR 7 (patch-008) and activated in CI by PR 9 (patch-010) of this stack.

Steps for the author:

• Commit message follows the guidelines.
• Appropriate Features or Test-tag pragmas were used.
• Appropriate Functional Test Stages were run.
• At least two positive code reviews including at least one code owner from each category referenced in the PR.
• Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions]

Ticket title is 'Add ASan/UBSan/TSan sanitizer checks to the GitHub Actions unit-test CI'
Status is 'In Progress'
Errors are Title of PR is too long
https://daosio.atlassian.net/browse/DAOS-18626

[daosbuild3]

Test stage Functional Cluster Box Medium MD on SSD completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18697/1/execution/node/1755/log