Save .git directory but not other git files

Update the pattern that specifies the files to keep
so the .git directory and its contents are saved
but the other git files like .gitreview and .gitignore
are not. Those will be imported from the cookiecutter
template.

Change-Id: I47acb07e7a12e0a0381e0aee2fa610929f685282
Fixes-bug: #1314664