acrn_ehl_crb: fix the incorrect configuration of timer IRQ priority

The default CONFIG_APIC_TIMER_IRQ_PRIORITY is 4, but it should be 1 for
ACRN. That's why the testcase failed due to no timer interrupt was
triggered.

And we also temporary adjust the testing IRQ for dynamic isr due to it
conflict with the IRQ of the APIC TSC deadline TIMER.

Fixes #36203.

Signed-off-by: Enjia Mai <enjiax.mai@intel.com>