[ROCM] Add rocjitsu e2e validation (#24913)

I want to enable e2e testing across all recent amdgpu / rcom targets via
rocjitsu, an amdgpu simulator, so that anyone with an x86 machine can
run those tests regardless of the local GPU or lack thereof.

Add a CPU-hosted ROCm e2e test helper for gfx942, gfx950, gfx1100,
gfx1201, and gfx1250. Reconfigure a regular IREE build and rebuild
iree-test-deps for each target, then run HIP tests with the simulator
from a pinned TheRock nightly.

Run each test in a fresh Mirage session with a watchdog and per-test
JUnit output. Propagate configure/build failures so stale artifacts
cannot produce a successful run.

Make the default native-test timeout configurable and label tests that
are too expensive to simulate. Keep those tests enabled for hardware
runs. Exclude TopK v2 from ROCm tests because its missing thread
distribution causes overlapping output writes on all five targets.

Use the target's preferred subgroup size when an executable does not
specify one, so gfx1250 defaults to wave32. Add regression coverage for
the default and explicit subgroup sizes.

Assisted-by: codex (gpt-6-astra)