[ci/ibex] temporarily remove pmp_full_random_test
[ci/ibex] temporarily remove pmp_full_random_test

this test is arbitrarily failing in regressions on a Spike timeout,
temporarily remove this to avoid blocking.

@udinator to fix this in the near future.

Signed-off-by: Udi Jonnalagadda <790cd677b6a22a419ffcfe0eb4293d8866eb70c9@google.com>

AmbiML/ibex,lowRISC/ibex,lowRISC/ibex,lowRISC/ibex,lowRISC/ibex,AmbiML/ibex,AmbiML/ibex,AmbiML/ibex