[test] Restrict thinlto icp IR test to little endian systems, and the...

[test] Restrict thinlto icp IR test to little endian systems, and the compiler-rt test to three tested platforms. (#76001)

- The IR test failed to import indirect callees on big-endian systems.
The raw profiles are generated on little-endian systems. Going to
require little-endian.
- Limit the compiler-rt test to three tested platforms.