Make cipd available in recipe bundle for dirmd

dirmd is present in the CIPD package, but running it gets:
./cipd_bin_setup.sh: line 25: ./cipd: No such file or directory

Bug: 416037494
Change-Id: I69b6640056ba9454737d02973119ee5cde771d80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6580852
Reviewed-by: Scott Lee <ddoman@chromium.org>
Commit-Queue: Scott Lee <ddoman@chromium.org>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Auto-Submit: Gavin Mak <gavinmak@google.com>

.gitattributes

@@ -16,6 +16,7 @@
 # Extensionless tools we want and support scripts.
 /autoninja*                   recipes
 /clang*                       recipes
+/cipd*                         recipes
 /dirmd                        recipes
 /download_from_google_storage recipes
 /fetch                        recipes