[tempest] Fix phantom test results from timing-data archive

[imatza-rh]

When discover-tempest-config fails and tempest run never executes,
stestr last --subunit picks up old test results from the timing-data
archive and reports them as if they passed in this run.

Root Cause

The timing-data archive
contains the full .stestr/ directory from previous runs — including old test
result files — not just the timing database that stestr uses for test scheduling.
When discover-tempest-config fails, those old results are picked up by the
unconditional generate_test_results call.

Example: https://sf.apps.int.gpc.ocp-hub.prod.psi.redhat.com/logs/25f/components-integration/25ffb2f08d194ccba0123053d8dfb21b/

Fix

Two changes in run_tempest.sh:

1. Extract only timing database files from the archive (times.dbm*)
   instead of the entire .stestr/ directory. stestr uses dbm.dumb which
   stores timing data as three files: .bak, .dat, .dir.

2. Guard result collection — track whether tempest run actually executed
   and skip move_tempest_log + generate_test_results when it did not.

Both layers are complementary: the tar filter prevents old results from being
extracted, and the execution guard prevents result collection when tests did
not run.

Testing

• Verified stestr source: uses from dbm import dumb as my_dbm for times.dbm
• Verified archive structure matches save_config_files output
• Tested tar wildcard extraction locally (only times.dbm.* files extracted)
• Verified RETURN_VALUE semantics are preserved (3 cases: both succeed, discover fails, tempest fails)
• Verified bash ERR trap interaction: if condition suppresses ERR trap (matching original && behavior)
• Verified rerun_failed_tests and check_expected_failures handle missing FAILED_TESTS_FILE correctly
• bashate passes clean

Closes: https://redhat.atlassian.net/browse/OSPNW-1674

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[kstrenkova]

The code itself looks good to me. Normally, I would also test it locally when I am reviewing a patch. However, due to having a load of work assigned at the moment, I will believe you tested the functionality 😄

[abays]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abays, imatza-rh, kstrenkova

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[imatza-rh]

/cherry-pick antelope

[openshift-cherrypick-robot]

@imatza-rh: new pull request created: #413

Details

In response to this:

/cherry-pick antelope

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