[RISCV] Merge some rvv intrinsic test cases that only differ by XLen type.

Instead of having a test for i32 XLen and i64 XLen, use sed to
replace iXLen with i32/i64 before running llc.

This change updates tests for intrinsics that operate exclusively
on mask values. It removes over 4000 lines worth of test content.
More merging will come in future changes.

Differential Revision: https://reviews.llvm.org/D117968