Rename XmlManifest.GetGroupsStr() to XmlManifest.GetManifestGroupsStr()

This makes it more clear what kind of groups it refers to.

Change-Id: I47369050d1436efcc77f3a69d5b7c99a536b23bc
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/528462
Tested-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

git_superproject.py

@@ -422,7 +422,8 @@ class Superproject:
             )
             return None
         manifest_str = self._manifest.ToXml(
-            filter_groups=self._manifest.GetGroupsStr(), omit_local=True
+            filter_groups=self._manifest.GetManifestGroupsStr(),
+            omit_local=True,
         ).toxml()
         manifest_path = self._manifest_path
         try: