Fix GPG status badge loading regressions

What does this MR do?

Fix some regressions on project, repository tree, and blob page around loading GPG signatures and displaying the GPG status badge.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conforms to the code review guidelines
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/49878, https://gitlab.com/gitlab-org/gitlab-ce/issues/49870, https://gitlab.com/gitlab-org/quality/nightly/issues/6, https://gitlab.com/gitlab-org/gitlab-ce/issues/49831