Use git_superproject.UseSuperproject() everywhere

Currently somewhere use git_superproject.UseSuperproject(), which checks
both the manifest config and user's config, and otherwhere use
manifest.manifestProject.use_superproject, which only checks the
manifest config. This causes Inconsistent behaviors for users who do not
set --use-superproject when doing repo init but have
repo.superprojectChoice in their git config.

Replace where using manifest.manifestProject.use_superproject with
git_superproject.UseSuperproject() to respect user's config and avoid
inconsistency.

Bug: 454514213
Change-Id: I1f734235cdd67b8a6915f1d05967d1aaa4d03f2a
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/561801
Commit-Queue: Jacky Liu <qsliu@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Jacky Liu <qsliu@google.com>

subcmds/upload.py

@@ -27,6 +27,7 @@ from error import SilentRepoExitError
 from error import UploadError
 from git_command import GitCommand
 from git_refs import R_HEADS
+import git_superproject
 from hooks import RepoHook
 from project import ReviewableBranch
 from repo_logging import RepoLogger
@@ -627,7 +628,7 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
         # If using superproject, add the root repo as a push option.
         manifest = branch.project.manifest
         push_options = list(opt.push_options)
-        if manifest.manifestProject.use_superproject:
+        if git_superproject.UseSuperproject(None, manifest):
             sp = manifest.superproject
             if sp:
                 r_id = sp.repo_id