## Context
Have Branching 2.0 as the default behaviour + remove it from feature
preview
Behaviour should match staging / prod if branching 2.0 feature preview
is toggled on
## To test
- [ ] Test branching flow in general for any oddities
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Chores**
* Removed the Branching 2.0 preview and cleared its persisted preview
setting; branching UI and branch editing are now available without
opt‑in.
* Simplified branch management flows and empty states by removing
preview-dependent conditions and tooltips.
* Made GitHub branch sync optional in create/edit forms and simplified
validation and submit behavior.
* "Create merge request" and related branch actions now render
consistently across the UI.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Joshen Lim
be0d05fb08