fix: disable automatic branching for free projects (supabase#46347)

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## Summary by CodeRabbit

* **Bug Fixes**
* Fixed an issue where the branch-per-PR setting in GitHub integration
connections could have an undefined value. The setting now defaults to a
valid state when creating or updating connections, ensuring consistent
and predictable behavior.

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Co-authored-by: Ali Waseem <waseema393@gmail.com>

Author: djhi

apps/studio/components/interfaces/Settings/Integrations/GithubIntegration/GitHubIntegrationConnectionForm.tsx

@@ -219,7 +219,7 @@ export const GitHubIntegrationConnectionForm = ({
         workdir: data.supabaseDirectory,
         supabase_changes_only: data.supabaseChangesOnly,
         branch_limit: Number(data.branchLimit),
-        new_branch_per_pr: data.new_branch_per_pr,
+        new_branch_per_pr: data.new_branch_per_pr ?? false,
       },
     })
 
@@ -268,7 +268,7 @@ export const GitHubIntegrationConnectionForm = ({
         workdir: data.supabaseDirectory,
         supabase_changes_only: data.supabaseChangesOnly,
         branch_limit: Number(data.branchLimit),
-        new_branch_per_pr: data.new_branch_per_pr,
+        new_branch_per_pr: data.new_branch_per_pr ?? false,
       },
     })