Speed up sonic_xcvr unit tests by patching time.sleep via autouse fixture

[aditya-nexthop]

Description

Add an autouse pytest fixture in tests/sonic_xcvr/conftest.py that
patches time.sleep for every test in the tests/sonic_xcvr package.

@pytest.fixture(autouse=True)
def _no_sleep():
    with patch("time.sleep"):
        yield

Motivation and Context

Several tests/sonic_xcvr tests exercise production code paths that
call time.sleep directly, without mocking it. The suite therefore
spends almost all of its wall time blocked in real sleeps:

Test	Count	Per-run	Total	Source of sleep
test_cmisCDB.py::test_start_fw_download	3	5.00s	15.0s	cmisCDB.py:288 — time.sleep(MAX_CDB_CMD_FOREGROUND_PROCESSING_TIME_tCDBF) (5s)
test_cmisCDB.py::test_validate_fw_image	3	5.00s	15.0s	cmisCDB.py:419 — same 5s constant
test_cmis.py::test_reset	1	2.00s	2.0s	cmis.py:1369 — time.sleep(2) after reset_module()
test_cmisCDB.py::test_run_fw_image	3	0.56s	1.7s	cmisCDB.py:459 — time.sleep(delay/1000) (delay ≈ 562 ms)
test_ccmis.py::test_set_tx_power	2	1.00s	2.0s	c_cmis.py:187 — time.sleep(1)

These 12 test invocations account for ~35.7s of a ~36.7s suite — about
97% of the runtime.

How Has This Been Tested?

Ran the full tests/sonic_xcvr suite before and after the change.

# Before
============================= 824 passed in 36.71s =============================

# After
============================= 824 passed in 1.07s ==============================

All 824 tests still pass; no behavior change. Suite is ~34× faster.

Additional Information (Optional)

[mssonicbld]

/azp run

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[prgeor]

@aditya-nexthop you mean test case running sleep is waste of time?

[aditya-nexthop]

yes, if it does nothing useful, especially in a unit test with no real hardware behind it?

[Copilot]

Pull request overview

This PR speeds up the tests/sonic_xcvr pytest suite by introducing an autouse fixture that patches time.sleep during each test run, eliminating real sleep delays from exercised production paths.

Changes:

• Add tests/sonic_xcvr/conftest.py with an autouse fixture that patches time.sleep for all tests under tests/sonic_xcvr.

[mssonicbld]

/azp run

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