Fix remaining offenses for cop rule Rake/Require

Problem

In !101740 (merged) we've added a new 👮 rule Rake/Require and generated TODOs for all offenses.

Proposed solution

Fix all remaining offenses for this cop by moving require and require_relative statements into task definitions.

List

• ee/lib/tasks/gitlab/spdx.rake - !111799 (merged)
• lib/tasks/gitlab/artifacts/migrate.rake - !111887 (merged)
• lib/tasks/gitlab/backup.rake - !111887 (merged)
• lib/tasks/gitlab/cleanup.rake - !111892 (merged)
• lib/tasks/gitlab/dependency_proxy/migrate.rake - !112065 (merged)
• lib/tasks/gitlab/docs/redirect.rake - !112123 (merged)
• lib/tasks/gitlab/graphql.rake - !112123 (merged)
• lib/tasks/gitlab/lfs/migrate.rake - !112123 (merged)
• lib/tasks/gitlab/metrics_exporter.rake - !112123 (merged)
• lib/tasks/gitlab/openapi.rake - !112123 (merged)
• lib/tasks/gitlab/assets.rake - !112385 (merged)
• lib/tasks/gitlab/packages/events.rake - !112386 (merged)
• lib/tasks/gitlab/packages/migrate.rake - !112387 (merged)
• lib/tasks/gitlab/pages.rake - !112387 (merged)
• lib/tasks/gitlab/refresh_project_statistics_build_artifacts_size.rake - !112390 (merged)
• lib/tasks/gitlab/terraform/migrate.rake - !112391 (merged)
• lib/tasks/gitlab/tw/codeowners.rake - !112391 (merged)
• lib/tasks/gitlab/x509/update.rake - !112394 (merged)
• lib/tasks/import.rake - !112394 (merged)
• lib/tasks/tokens.rake - !115090 (merged)
• qa/tasks/webdrivers.rake - !115107 (merged)

Implementation guide

1. 🔍 Pick an file entry from .rubocop_todo/rake/require.yml.
2. 💪 Move require/require_relative statements into task definition.
3. ✅ Verify that the changed rake task still works.
4. ❌ Remove fixed file from .rubocop_todo/rake/require.yml.
5. 👮 Verify that RuboCop does not flag anymore via rubocop --only Rake/Require <picked file entry>.
6. 🔀 Create an MR and add Contributes to #391459 to the MR description.
7. ✍ Community contribution may contain the git trailer Changelog: other. See docs.
8. ✔ Tick the checkbox of the fixed entry and mention the MR next to it.
9. 🎉 Celebrate!

Example: !111799 (merged)