[13/15][Clang][RISCV][NFC] Remove repeating test cases under rvv-intrinsics-autogenerated

These files were oversights in D141198. The test cases are now under its
exact mnemonics. For example, test cases of `vle8`, `vle16`, `vle32`,
and `vle64` were under `vle.c`. Now they are exist under `vle8.c`,
`vle16.c`, `vle32.c`, and `vle64.c`, respectively.

This is the 13th commit of a patch-set that aims to change the default policy
for RVV intrinsics from TAMU to TAMA.

Please refer to the cover letter in the 1st commit (D141573) for an
overview.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D141792