Fix caplog access during teardown report creation

[scapalive]

Fixes #14436.

"LogCaptureFixture" now retains the logging handler and per-phase records mapping created for its test item, instead of retrieving them from "item.stash" on every access.

The logging plugin removes those stash entries at the end of teardown. However, teardown "pytest_runtest_makereport" consumers may still retain the fixture through "item.funcargs". Accessing "caplog.text" or "caplog.get_records()" at that point could therefore raise "KeyError".

The regression test covers both access paths during teardown report creation.

[scapalive]

The failing "build (ubuntu-py311)" job appears unrelated to this change.

I reproduced the relevant tests locally on the PR HEAD ("f129e232f459b7ecb9b4e85ef69f70f0fd62d832"):

• "TestPDB::test_pdb_unittest_postmortem": 30/30 runs passed
• caplog regression test: passed
• complete "testing/logging/test_fixture.py" and "testing/test_debugging.py" suites: 82 passed, 1 skipped, 6 xpassed

The PDB test does not use "caplog", so "LogCaptureFixture" is not instantiated in that path. I could not reproduce the timeout or identify a causal connection with this patch. The same commit also had a previous successful CI run.

Could a maintainer please rerun the failed job?