Skip pylint's primer tests, which race each other under pytest-xdist

[thomasjm]

build-sample-environments (Linux, x86_64-linux) failed on a cold cache with:

error: Cannot build '/nix/store/...-python3.11-pylint-3.3.7.drv'
  > FAILED tests/testutils/_primer/test_primer.py::TestPrimer::test_compare[message_changed]
  > AssertionError: assert '' == '🤖 **Effect o...mmit v2.14.2*'
  > ============ 1 failed, 996 passed, 250 skipped, 5 xfailed in 8.20s =============

It only shows up when pylint is built from source, so it stays hidden until a cache eviction and
then takes out sample environments on whatever branch happens to arrive first. It hit my
stable-Nixpkgs branch and looked like a regression there; it isn't.

Why it is flaky

Every test in that module funnels through one helper:

with patch("sys.argv", new_argv):
    Primer(PRIMER_DIRECTORY, PACKAGES_TO_PRIME_PATH).run()
with open(PRIMER_DIRECTORY / "comment.txt", encoding="utf8") as f:
    content = f.read()

PRIMER_DIRECTORY is a single fixed path, tests/.pylint_primer_tests/, shared by every
test_compare parametrization plus test_compare_batched and test_truncated_compare. nixpkgs runs
the suite under pytest-xdist, so those land on different workers in the same working directory and
overwrite each other's comment.txt. A worker that reads while another is mid-write gets an empty
file, which is exactly the assert '' == ... in the failure.

That also explains why it is specifically python3.11-pylint: the whole TestPrimer class is
skipif sys.version_info[:2] != (3, 11), so no other interpreter runs these at all.

The fix

Add the module to disabledTestPaths, alongside the two entries nixpkgs already disables there.
These tests cover pylint's own CI primer tooling -- comparing lint output between two git revisions
of upstream packages -- which is not something we ship or depend on.

Testing

Local rebuild of python311Packages.pylint from source, unpatched: 997 passed, 250 skipped,
5 xfailed -- it passes here, which confirms the test is flaky rather than broken, and is why this
only ever shows up under CI's scheduling.

With the override: 991 passed, 250 skipped, 5 xfailed -- the 6 primer tests are gone and nothing
else changes. Verified the override reaches the package: disabledTestPaths goes from
["tests/benchmark" "tests/pyreverse/test_writer.py"] to that plus
"tests/testutils/_primer/test_primer.py", and the derivation hash changes.