tests/gunit: disable execution with --gtest_shuffle

tests/gunit: disable execution with --gtest_shuffle

Some Google tests rely on being run in a specific order, with certain
tests depending on the successful completion of previous ones. Passing
the --gtest_shuffle option can break this sequence, potentially leading
to test failures or inconsistent results.

Until the test suite is updated to support randomized execution, skip
running tests when --gtest_shuffle is used.

Acked-by: Tom Hromatka <tom.hromatka@oracle.com>
Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>