fix: allow shared/re-used deps lists across py_test targets

[racosta]

If there is a common list of dependencies which are shared across multiple py_test targets and pytest_main is set to True on both of them there is a build issue because the deps list is mutated and //py/private:default_pytest_main is included twice/multiple times.

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Changes are visible to end-users: no

Test plan

• New test cases added

  • Added two tests to demonstrate the behavior. Both must be built together to demonstrate the build issue:

    1. //py/tests/py-test:test_pytest_main_shared_deps_a
    2. //py/tests/py-test:test_pytest_main_shared_deps_b

    bazel test //py/tests/py-test:test_pytest_main_shared_deps_a //py/tests/py-test:test_pytest_main_shared_deps_b

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[aspect-workflows]

Bazel 8 (Test)

2 test targets passed

Targets

//py/tests/py-test:test_pytest_main_shared_deps_a [k8-fastbuild]                 659ms
//py/tests/py-test:test_pytest_main_shared_deps_b [k8-fastbuild]                 714ms

Total test execution time was 1s. 177 tests (98.9%) were fully cached saving 1m 4s.

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Bazel 9 (Test)

2 test targets passed

Targets

//py/tests/py-test:test_pytest_main_shared_deps_a [k8-fastbuild]                 755ms
//py/tests/py-test:test_pytest_main_shared_deps_b [k8-fastbuild]                 706ms

Total test execution time was 1s. 176 tests (98.9%) were fully cached saving 1m 10s.

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Bazel 8 (Test)

e2e

All tests were cache hits

103 tests (100.0%) were fully cached saving 1m 21s.

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Bazel 9 (Test)

e2e

All tests were cache hits

103 tests (100.0%) were fully cached saving 55s.

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Bazel 8 (Test)

examples/uv_pip_compile

All tests were cache hits

1 test (100.0%) was fully cached saving 444ms.

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Buildifier      Gazelle