[lld] [lld][test] filecheck typo fixes (PR #93471)

[via llvm-commits]

klensy wrote:

tests with filecheck directives, but without `RUN:` with filecheck
```
lld\test\COFF\pdb_char8_t.ll
lld\test\ELF\aarch64-cortex-a53-843419-thunk-align.s
lld\test\ELF\arm-thumb-branch-rangethunk.s
lld\test\ELF\comdat-discarded-gdb-index.s
lld\test\ELF\dso-undef-size.s
lld\test\ELF\lto\ctor-dtor-alias2.ll
```

https://github.com/llvm/llvm-project/pull/93471