[XLA:GPU] Improve testing of algorithm support
[XLA:GPU] Improve testing of algorithm support

- Test that ALG_DOT_BF16_BF16_F32_X3 and ALG_DOT_BF16_BF16_F32_X6 gets dispatched to Triton.
- Add small tests ([2, 16] x [16, 2] -> [2, 2] in addition to [32, 32] x [32, 32] -> [32, 32]). This makes sure that we also rewrite small matmuls where needed because of the special algorithm requested.
- Change IrEmitterTritonTests to also test ALG_DOT_BF16_BF16_F32_X3 and ALG_DOT_BF16_BF16_F32_X6 support using the new algorithm parameter, not just the debug flag.
