tests: coredump: skip acrn_ehl_crb

The coredump tests output quite a large amount of data into
the console. However, the ACRN console only has very limited
history (comparatively), such that twister is unable to
match the necessary strings to consider the tests passed.
So skip those tests on acrn_ehl_crb.

Fixes #40887

Signed-off-by: Daniel Leung <daniel.leung@intel.com>