[X86] Add new llvm#134979 test cases for gather scalar (llvm#137416)

We are adding new test cases to see the transformation impact due to llvm#134979.

These are similar to previous commit #688c3ffb057a87b86c6c1e77040418adf511efbb.

Handling struct with two member and different vector factor.

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Co-authored-by: Rohit Aggarwal <[email protected]>

Author: 2 people