Add managed-apps section in log explorer

What does this MR do?

This adds the "managed apps" dropdown section for the environments dropdown inside the log explorer

#208790 (closed)

Screenshots

Screen_Recording_2020-07-15_at_9.56.52

P.S. The logs are not working since my cluster is acting up 🙈

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content