[dv] Fix directed-test configuration and scheduling

[kulan-pal]

Three small fixes to the directed-test flow in dv/uvm/core_ibex. None changes which
tests run on the baseline; they are prerequisites for directed tests that need a
plusarg of their own (Zcmp and dummy-instruction tests in follow-up PRs, see #2461).

sim_opts is silently dropped from directed-test entries

scripts/run_rtl.py reads sim_opts from the test options for both riscv-dv and
directed tests, but the pydantic schema for directed_testlist.yaml
(scripts/directed_test_schema.py) has no such field, so pydantic's default
extra = "ignore" discarded it. A directed test could not pass a plusarg through its
own entry. The field is added to DConfig as Optional[str] = None: existing
entries stay valid, and a config default can still be overridden per test.

A test with N rtl_params entries is scheduled N times

In scripts/ibex_cmd.py::filter_tests_by_config the accepting append sat inside
the loop over rtl_params, so a test listing N parameters was appended N times:
make warned about duplicate targets and regr.log counted every seed N times.
Every existing entry lists one parameter, which hid it. The append moves to the
loop's else: clause, which runs once and only when no parameter caused a break.

directed_testlist.yaml regenerates differently per locale

directed_tests/gen_testlist.py listed the vendored test directories with ls,
whose order follows the locale's collation, so the committed YAML could not be
checked against its generator. The listings now come from sorted(os.listdir()),
which is code-point order on every machine. The regenerated YAML is included.

Verification

Baseline 34b07057.

• Regeneration is byte-identical after this change. The 944 entries and their
  contents are unchanged; only the order of a few vendored tests differs. With the
  unmodified generator, running under the C locale produces a different file from the
  committed one.
• Python only: filter_tests_by_config on the opentitan config returns a test with
  two rtl_params entries twice before this change and once after; one-parameter,
  no-parameter and rejected tests behave the same before and after.
• End to end (VCS U-2023.03-SP2, Spike ibex_cosim, IBEX_CONFIG=opentitan): a
  directed test with two rtl_params entries and sim_opts: +disable_cosim=1 is
  scheduled once and the plusarg appears on the simulator command line. Existing
  directed tests and riscv_arithmetic_basic_test pass unchanged.
• util/lint_commits.py --no-merges clean.

Disclosure

Per CLA section 9: the analysis and code in this PR were produced with the
assistance of an AI coding tool (Claude Code) and independently reviewed with a
second tool (OpenAI Codex). I have reviewed and understood every change and take
full responsibility for it.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Rn6C7Eyq1LchFeP9w6up9P

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[kulan-pal]

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