cos-tools: release cos-gpu-installer v2.7.0
This release runs the persistenced and nvidia-gridd daemons as part of the cos-gpu-installer, previously they were run from cos-extensions.

BUG=b/502284908
TEST=Tested in cos-review.git.corp.google.com/c/cos/tools/+/149184 and https://cos-review.git.corp.google.com/c/cos/cos-extensions/+/149046.
RELEASE_NOTE=None

Change-Id: I0435d6303da1a2732e371f1f0558a47bf22aae84
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/149963
Reviewed-by: He Gao <hegao@google.com>
Reviewed-by: Kevin Berry <kpberry@google.com>
Cloud-Build: 228075978874@cloudbuild.gserviceaccount.com <228075978874@cloudbuild.gserviceaccount.com>
Tested-by: Miri Amarilio <mirilio@google.com>