Remove XFAIL from GSVector.test

[hekota]

This test is now passing since llvm/llvm-project#167729 issue is fixed.

[bogner]

Looks like this asserts for SPIRV - https://github.com/llvm/offload-test-suite/actions/runs/19845383191/job/56861669090?pr=535#step:12:446

Assertion failed: Opcode == SPIRV::OpPtrAccessChain || Opcode == SPIRV::OpInBoundsPtrAccessChain || (getImm(I.getOperand(4), MRI) && foldImm(I.getOperand(4), MRI) == 0) && "Cannot translate GEP to OpAccessChain. First index must be 0.", file E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVInstructionSelector.cpp, line 3359