[TF-M] Disable FLIH tests in CI

Hi All,

it is spotted that FLIH tests failed recently and blocks CI verification. We need to dig into it and found the reason. To avoid blocking the daily work, we will temporarily turn FLIH tests off, and recover when solved.

Background: Sometimes the test application stuck in waiting for interrupts even the interrupt is properly configured. If someone got solutions for similar problems please share your info, thank you in advance.

Best Regards, Xinyu