test(probes): un-shadow leakreplay probe structure test

[anxkhn]

Two test functions in tests/probes/test_probes_leakreplay.py were both named
test_leakreplay_probe_structure. Python binds the later def over the earlier
one in the module namespace, and pytest collects test functions from that
namespace by name, so the first definition (the broad structure test
parametrized over LEAKREPLAY_PROBES, all 16 leakreplay probes) was silently
overwritten and never collected. Only the second definition ran, and it is
parametrized over CLOZE_PROBES (the 8 Cloze/ClozeFull probes). As a
result the 8 Complete/CompleteFull leakreplay probes had no structure, tag,
or %-escape coverage at all.

This renames the second, Cloze-specific function to
test_leakreplay_cloze_probe_structure (its @pytest.mark.parametrize already
targets CLOZE_PROBES) so both tests are now collected and run.

Un-shadowing the broad test surfaced a latent bug in that test: it looked the
probe class up with the fully qualified plugin name, e.g.
getattr(garak.probes.leakreplay, "probes.leakreplay.PotterComplete"), which
raises AttributeError. Because the test had never actually executed, the
defect had gone unnoticed. It is fixed by resolving the bare class name with
klassname.split(".")[-1], the same idiom already used elsewhere in the test
suite (e.g. tests/plugins/test_plugins.py, tests/detectors/test_detectors.py,
tests/generators/test_generators.py).

Net effect: the Complete/CompleteFull probes regain full structure/tag/
%-escape validation, and the two tests no longer collide.

Verification

• Run the tests and ensure they pass python -m pytest tests/
  • python -m pytest tests/probes/test_probes_leakreplay.py -> 28 passed
    (was 20 before: the broad 16-case test was not being collected).
• Verify collection is restored:
  python -m pytest tests/probes/test_probes_leakreplay.py --collect-only
  now shows 16 test_leakreplay_probe_structure[...] cases (all
  LEAKREPLAY_PROBES) plus 8 test_leakreplay_cloze_probe_structure[...]
  cases (was 8 total).
• Verify the reinstated cases do real work: PotterComplete (a
  Complete probe) carries the expected tags and the %-escape handling the
  broad test asserts, so the newly collected cases exercise real assertions,
  not vacuous passes.
• Formatting unchanged: black --check tests/probes/test_probes_leakreplay.py.

No production code changes; test-only, one file, +2/-2.

Not a duplicate

No open PR touches tests/probes/test_probes_leakreplay.py. The nearby
test-coverage PRs add different files (#1853 adds detector/probe tests for other
modules, including tests/detectors/test_detectors_leakreplay.py; #1818 adds a
new probe and its own test file), and no open issue tracks this shadowed
duplicate-name test.

AI assistance

AI assistance was used to prepare this change. I have reviewed every changed
line, reproduced the missing-coverage behaviour and the fix locally, and ran the
test suite for the affected file.

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Notes for maintainers scope

• Follows test(probes): conventional-commit style used across the repo.
• DCO sign-off and Co-authored-by: Claude trailer are in the commit.
• No new dependencies, no base-class edits, no SPDX header (nothing imported
  under another license).