[clang-tidy][NFC] Improved hungarian notation regression test at post-commit review

Improve the (`D144510`)[https://reviews.llvm.org/D144510] patch with prefix string. Using "my" instead of "cust" would increase
readability.

Take some examples:
- const char* `custszNamePtr` = "Name"; --> `myszNamePtr`
- uint8_t `custu8ValueU8` = 0; --> `myu8ValueU8`
- DWORD `custdwMsDword` = 0; --> `mydwMsDword`

Reviewed By: PiotrZSL

Differential Revision: https://reviews.llvm.org/D148314