tests/kernel/common: Skip bitarray tests when KERNEL_COHERENCE

Kernel objects that contain embedded synchronization structures like
spinlocks can't be palced in the (cached/incoherent) stack memory on
coherence platforms like intel_adsp.

The normal fix in a test case is just to make the offending data
static, but that's painful here because SYS_BITARRAY_DEFINE declares
two objects (i.e. you can't put a "static" in front of it as with
similar macros) and it happens to be used in this case to define local
variables with collliding names, so I'd have to go in and rename
everything.

And there's little value anyway.  Bitarrays are nearly-pure data
structures and extremely unlikely to show up platform-dependent
behavior.

Fixes #35242

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>