Extend dast profile instance variable with branch

- Adds new field to @dast_profile ivar
- Updates specs to reflect change

ee/app/controllers/projects/on_demand_scans_controller.rb

@@ -31,6 +31,7 @@ def edit
         id: dast_profile.to_global_id.to_s,
         name: dast_profile.name,
         description: dast_profile.description,
+        branch: { name: dast_profile.branch_name },
         site_profile_id: DastSiteProfile.new(id: dast_profile.dast_site_profile_id).to_global_id.to_s,
         scanner_profile_id: DastScannerProfile.new(id: dast_profile.dast_scanner_profile_id).to_global_id.to_s
       }

ee/spec/requests/projects/on_demand_scans_controller_spec.rb

@@ -107,6 +107,7 @@
             id: global_id_of(dast_profile),
             name: dast_profile.name,
             description: dast_profile.description,
+            branch: { name: dast_profile.branch_name },
             site_profile_id: global_id_of(DastSiteProfile.new(id: dast_profile.dast_site_profile_id)),
             scanner_profile_id: global_id_of(DastScannerProfile.new(id: dast_profile.dast_scanner_profile_id))
           }.to_json