Also delete local release tag (#4943)

If the tag exists in public, then it exists locally too since we fetched all of
public when adding it as a remote. Also delete this local tag so it doesn't fail
when we recreate it.

buildspecs/release-to-github.yml

@@ -24,6 +24,7 @@ phases:
     - |
       if [ `git ls-remote --tags public  | grep refs/tags/$RELEASE_VERSION | wc -l` -ge "1" ]; then
         git push public :refs/tags/$RELEASE_VERSION
+        git tag --delete $RELEASE_VERSION
       fi
     - git tag -a $RELEASE_VERSION -m "AWS SDK for Java v2 ($RELEASE_VERSION)"
     -