Handle multiple repos listed in staging-repo.

Handle multiple repos listed in staging-repo.

Handle multiple repos listed in staging-repo for ODL.

Also multiple release files in the same commit will not work.
exiting if this case is detected

Also
git diff HEAD^1 --name-only
is bad. if there is another merge it fails.

Change to
git diff-tree --no-commit-id -r $GERRIT_PATCHSET_REVISION \
    --name-only -- "releases/"

StrictHostKeyChecking is enabled on the builder.
disabled

Also needed to change

{jenkins-ssh-credential}
to
{jenkins-ssh-release-credential}

Also
Give group ``self-serve-release`` Forge Committer rights
on refs/tags/
and allow on Create Signed Tag Create Annotated Tag

Also
- file-id: signing-pubkey
target: SIGNING_PUBKEY

Also fix nexus url needs https://

Issue: RELENG-2129
Change-Id: I55dc0a4022f93a6c3c0f389c04c88c38c53eff64
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>