reclient_cfgs: remove unused nacl configs

Fix untracked files

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        buildtools/reclient_cfgs/nacl/rewrapper_mac.cfg
        buildtools/reclient_cfgs/nacl/rewrapper_windows.cfg
        buildtools/reclient_cfgs/nacl/win-cross/

These files were provided reclient_cfgs cipd for nacl,
but we don't need them now (no nacl usage for mac and windows)

Bug: b/353878534, b/354804085
Change-Id: Iee790a8a74f2e890b9d6081aeeadb8acf74e5fef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5733052
Reviewed-by: Junji Watanabe <jwata@google.com>
Commit-Queue: Fumitoshi Ukai <ukai@google.com>
Auto-Submit: Fumitoshi Ukai <ukai@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1331524}