[X86] Backport new intrinsic and instruction changes in AVX10.2

[phoebewang]

This is a single request to backporting #131592, #132362, #132397, #132405, #132414, and #132426.

#131592 is saturation intrinsic naming change that aligned with GCC;
#132362 is a revert of prior merged new YMM rounding variants of existing instructions;
#132397, #132405, #132414, and #132426 remove the YMM rounding variants from new introduced AVX10.2 instruction. Together with #132362, they are to reflect the latest change of AVX10 white paper: https://cdrdv2.intel.com/v1/dl/getContent/784343

Although the changes look big, they are just straightforward removal or renaming, the risk is low. I think back porting to LLVM20 can reduce the scope of people who may use the unsupported instructions and future compatibility issues when switching LLVM20 to future version.

[phoebewang]

/cherry-pick phoebewang@74bbc44 phoebewang@3cad497 phoebewang@da7083d phoebewang@f76100d phoebewang@3757a76 phoebewang@fa4e3e4

[llvmbot]

Failed to cherry-pick: phoebewang@fa4e3e4

https://github.com/llvm/llvm-project/actions/runs/14099165159

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

[llvmbot]

Failed to cherry-pick: phoebewang@74bbc44

https://github.com/llvm/llvm-project/actions/runs/14099184224

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

[llvmbot]

@llvm/issue-subscribers-backend-x86

Author: Phoebe Wang (phoebewang)

This is a single request to backporting #131592, #132362, #132397, #132405, #132414, and #132426.

#131592 is saturation intrinsic naming change that aligned with GCC;
#132362 is a revert of prior merged new YMM rounding variants of existing instructions;
#132397, #132405, #132414, and #132426 remove the YMM rounding variants from new introduced AVX10.2 instruction. Together with #132362, they are to reflect the latest change of AVX10 white paper: https://cdrdv2.intel.com/v1/dl/getContent/784343

Although the changes look big, they are just straightforward removal or renaming, the risk is low. I think back porting to LLVM20 can reduce the scope of people who may use the unsupported instructions and future compatibility issues when switching LLVM20 to future version.