[MISC] Consolidate FP8 kv-cache tests

[comaniac]

• Consolidate the tests introduced by [Bugfix] Address #8009 and add model test for flashinfer fp8 kv cache. #8013 along with other fp8 kv-cache tests.
• Re-enable fp8 model tests. We now checking the logprobs of first 4 tokens instead of checking the output tokens.

cc @robertgshaw2-neuralmagic @mgoin @pavanimajety @jon-chuang

[jon-chuang]

I guess this will circumvent #8051 and ignore that particular case; simply test on a smaller subset of models

[comaniac]

I guess this will circumvent #8051 and ignore that particular case; simply test on a smaller subset of models

Yeah I don't think we need to test that model for this test.

[mgoin]

LGTM!

[pavanimajety]

LGTM, thanks for the test!