Default Branch name does not change when changing the Default Branch name for a project that was disconnected from a repository

Steps to reproduce:

1. Open the Unity Hub
2. Click the "New project" button
3. Set Source control provider to GitHub
4. Connect Personal Access Token
5. Create project
6. Exit the Editor
7. Open the foldout of the created project in the Hub
8. Click the "Disconnect from GitHub" button
9. Click the "Connect to source control" button
10. Open the Additional configuration foldout
11. Change the Default branch name to "asddd"
12. Click the "Connect" button
13. Observe the branch name

Actual results: In both Hub and GitHub the branch name is "main"

Expected results: In both Hub and GitHub the branch name is "asddd"

Reproducible with versions: 3.17.2

Tested on (OS): MacOS Silicon Tahoe 26.3

Notes:

• Changing default branch name works properly when creating a project, the issue is when the project was already connected to a repository but was disconnected and connected to a new repository
• If the project is created with a different branch name, in the reproduction instead of "main" the branch will fallback/reset to whatever the name was used when the project was created