fix Maven cache outside project folder (Issue gitlab-org/gitlab-ce#27675)

What does this MR do?

fix cache outside repository in CI Yaml template for Maven

Are there points in the code the reviewer needs to double check?

No

Why was this MR needed?

The template currently used use a cache outside of the project folder, see issue gitlab-org/gitlab-ce#27675

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

gitlab-org/gitlab-ce#27675