Resolve "Add RuboCop rule to limit file names to 100 characters"

Description of the proposal

In a Docker build (https://dev.gitlab.org/gitlab/omnibus-gitlab/-/jobs/6643009) we ran into the issues, because of longstanding issue with RubyGems: https://github.com/rubygems/rubygems/issues/1376.

To prevent this from happening again, we should add a RuboCop rule that limits the length of file names to 100 characters (not just bytes).

Check-list

• Make sure this MR enables a static analysis check rule for new usage but ignores current offenses // there are no offenses ATM
• Create a follow-up issue to fix the current offenses as a separate iteration: ISSUE_LINK // there are no offenses ATM
• Mention this proposal in the relevant Slack channels (e.g. #development, #backend, #frontend)
• If there is a choice to make between two potential styles, set up an emoji vote in the MR:
  • CHOICE_A: 🅰
  • CHOICE_B: 🅱
  • Vote yourself for both choices so that people know these are the choices
• The MR doesn't have significant objections, and is getting a majority of 👍 vs 👎 (remember that we don't need to reach a consensus)
• (If applicable) One style is getting a majority of vote (compared to the other choice)
• (If applicable) Update the MR with the chosen style
• Follow the review process as usual
• Once approved and merged by a maintainer, mention it again:
  • In the relevant Slack channels (e.g. #development, #backend, #frontend)
  • (Optional depending on the impact of the change) In the Engineering Week in Review

/cc @gitlab-org/maintainers/rails-backend

Closes #204753 (closed)