Default templates inside project for issues and MRs in Free
## Proposal
Be able to assign a MR template by default to all MR instead of selecting it every time.
## Links / references
https://forum.gitlab.com/t/set-mr-template-as-default/3995
## Documentation to update
If this feature is moved, we'll need to update [this documentation page](https://docs.gitlab.com/ee/user/project/description_templates.html#set-a-default-template-for-merge-requests-and-issues) and other mentions in the docs and on about.gitlab.com.
Docs style guide on documenting moving a feature to another tier: https://docs.gitlab.com/ee/development/documentation/styleguide/index.html#version-text-in-the-version-history
## Current Status
After reviewing this proposal and the supporting evidence in this confidential issue (https://gitlab.com/gitlab-com/Product/-/issues/2631), there was unanimous approval for moving default description templates to `Free`.
## Implementation Tasks
- [ ] Move related code from EE to CE for default Issue Templates
- [ ] Move related code from EE to CE for default MR Templates
- [ ] Documentation update
issue