LAKITU: remove COS specific helper scripts

COS helper scripts moved to a dedicated repo that will be mounted to
the same location so remove to avoid confusion.

BUG=b/306515214
TEST=presubmit
RELEASE_NOTE=None

Change-Id: Ia2391e0eaf6995930ac386c00ef1f3bba31bd3c9
Reviewed-on: https://cos-review.googlesource.com/c/third_party/platform/crosutils/+/59736
Tested-by: Oleksandr Tymoshenko <ovt@google.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>