[python_testing] Add TC-ELDIST-2.1 and run it against electrical-protection-app (#73463)

* [python_testing] Add TC-ELDIST-2.1 and run it against electrical-protection-app

Second slice of the Electrical Protection example app sequence: wire the app
into the test harness and add the first Python test that exercises it.

- Register the app as a test-harness target (scripts/tests/local.py) and build
  it in the test job (tests.yaml), exporting ELECTRICAL_PROTECTION_APP.
- Add TC_ELDIST_2_1.py, targeting ${ELECTRICAL_PROTECTION_APP} on endpoint 1.

This script was previously blocked: the Electrical Distribution cluster server
was not present in any example app, so it could not exercise a DUT and had to be
listed in test_metadata.yaml as excluded. The app added in #73462 resolves that,
so the script runs in CI and no exclusion entry is needed.

Testing: run against the app locally, commissioning on-network:

  scripts/tests/run_python_test.py --factory-reset \
    --app out/epa-pr1/chip-electrical-protection-app \
    --app-args "--discriminator 1234 --KVS kvs1" \
    --script src/python_testing/TC_ELDIST_2_1.py \
    --script-args "--storage-path admin_storage.json \
      --commissioning-method on-network --discriminator 1234 \
      --passcode 20202021 --endpoint 1"

  Summary for test class TC_ELDIST_2_1:
  Error 0, Executed 1, Failed 0, Passed 1, Requested 1, Skipped 0

Depends on #73462 (the app) and #73380 (the cluster server).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* [python_testing] Use lazy % formatting in TC-ELDIST-2.1 logging

ruff G004 rejects f-strings in logging calls. The script predates that rule
being enforced, so its five log.info() calls tripped Lint Code Base.

Testing: ruff check passes; the test still passes against
electrical-protection-app (Executed 1, Failed 0, Passed 1) and the reformatted
lines render correctly, e.g. "MaxContinuousCurrent: 100000 mA".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* [python_testing] Copyright year 2026 in TC-ELDIST-2.1

Review feedback from @jamesharrow on #73463. The script was drafted in 2025 but
first lands in the repository in 2026.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* [TC-ELDIST-2.1] Address review: align step text with the test plan

Step descriptions and expectations now reproduce the test plan's wording
with macros expanded, using the expectation= argument for the Expected
Outcome column rather than folding it into the description.

Use matter_asserts in place of hand-rolled checks: assert_valid_int64 for
the two int64 attributes, assert_int_in_range for NumberOfPoles,
assert_valid_enum for EndOfLife, assert_valid_bool for
ServiceEntranceRated.

Drop the assert_is_not_none calls. read_single_attribute_check_success
already asserts on a None result, so they could never fire.

Remove the write-to-read-only step, which was removed from the test plan,
and correct the docstring: X is Nullable, not Fixed.

* [TC-ELDIST-2.1] Match the docstring to the test plan's Purpose

Use the test plan's Purpose sentence verbatim with macros expanded,
rather than a paraphrase plus an attribute list that would go stale.

* [TC-ELDIST-2.1] Enforce the schema upper bounds

MaxContinuousCurrent and MaxVoltage are capped at 0x3FFFFFFFFFFFFFFF by
the cluster XML, which assert_valid_int64 does not enforce. Use
assert_int_in_range for both, which covers the integer type check and
each bound in one call.

EndOfLife values outside the enum decode to kUnknownEnumValue, still an
instance of the enum, so assert_valid_enum alone accepted them. Reject
that value explicitly.

* Enable tracing support in the electrical-protection-app

The test harness starts every Linux example app with --trace-to, but that
option is only registered when ENABLE_TRACING is set, which comes from
matter_enable_tracing_support in the app's own args.gni. Without it the app
rejected the argument and exited before commissioning:

  chip-electrical-protection-app: Unknown option: --trace-to
  Failed to init Linux App: examples/platform/linux/Options.cpp:1051:
      Error 0x0000002F

TC-ELDIST-2.1 then failed while establishing PASE, never reaching a test
step. closure-app sets the same flag in its args.gni for the same reason.

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Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>