tests: interrupt: fix testcase.yaml

The test itself handles correctly whether gen_isr_table
style dynamic interrupts are supported or not, there's
no need for an alternate scenario.

The tests work fine on riscv32 now, remove the exclusion.
Add a github link as to why Nios II is still excluded.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>