oeqa/gitarchive: Push tag before copying log files

oeqa/gitarchive: Push tag before copying log files

Resulttool creates a git tag in the yocto-testresults git and then
copies log files to a newly created folder on the NFS share, whose name
is controlled by the name of this git tag. As tags are unique, the
folder name is also unique, preventing any clash between different
builds.

Today, the tag is pushed from the calling script, so after the folder is
copied. This can lead to some issues if for any reason the tag is not
pushed. This might also lead to some race condition. Allow to push the
tag before coying data, in order to prevent these issues, and add a
warning if the calling script choose to not push the tag but still copy
the log files on the NFS share.

Fixes [YOCTO #15696]

Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>