install goma client cipd package in depot_tools.

should not use $MYPATH/goma_ctl in cipd_bin_setup
since $MYPATH/goma_ctl uses cipd_bin_setup in itself,
so causing recursive calls.
invoke python to run .cipd/goma_ctl.py in cipd_bin_setup
instead.

Bug: b/77663154
Change-Id: I9f82c766a886a2acfb899e3594e5f05a7b7bc75a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1866350Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Fumitoshi Ukai <ukai@chromium.org>