Create tags in project in post creation worker

What does this MR do and why?

As per &8741, we needed predefined tags in projects that can be used for timeline events.

This MR adds those timeline event tags whenever any project is created.

This is done in a post creation worker.

Screenshots or screen recordings

NA

How to set up and validate locally

1. Create a new project.
2. Run Project.find(<project_id_from_step_1>).incident_management_timeline_event_tags inside rails console.
3. Check that tags are created with Start time and End time names.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #373853 (closed)