kunit: executor: Fix a memory leak on failure in kunit_filter_tests

In the Linux kernel, the following vulnerability has been resolved:

kunit: executor: Fix a memory leak on failure in kunit_filter_tests

It's possible that memory allocation for 'filtered' will fail, but for the

copy of the suite to succeed. In this case, the copy could be leaked.

Properly free 'copy' in the error case for the allocation of 'filtered'

failing.

Note that there may also have been a similar issue in

kunit_filter_subsuites, before it was removed in "kunit: flatten

kunit_suite*** to kunit_suite** in .kunit_test_suites".

This was reported by clang-analyzer via the kernel test robot, here:

https://lore.kernel.org/all/[email protected]/

And by smatch via Dan Carpenter and the kernel test robot:

https://lore.kernel.org/all/[email protected]/