[NFC][clang] Inclusive language: replace masterPort with mainPort

[NFC] This patch replaces `masterPort` with `mainPort` in these
testcases.

Reviewed By: ZarkoCA

Differential Revision: https://reviews.llvm.org/D113505

GitOrigin-RevId: 7a14244cc645bbbcbf5056e7a00fadbb339e92ed
7 files changed