Fixes the delete source branch checkbox not working

This fixes the delete source branch checkbox not working
with the GraphQL flag enabled.

app/assets/javascripts/vue_merge_request_widget/components/states/ready_to_merge.vue

@@ -56,7 +56,10 @@ export default {
           mergeRequestsFfOnlyEnabled: data.project.mergeRequestsFfOnlyEnabled,
           onlyAllowMergeIfPipelineSucceeds: data.project.onlyAllowMergeIfPipelineSucceeds,
         };
-        this.removeSourceBranch = data.project.mergeRequest.shouldRemoveSourceBranch;
+        this.removeSourceBranch =
+          data.project.mergeRequest.shouldRemoveSourceBranch ||
+          data.project.mergeRequest.forceRemoveSourceBranch ||
+          false;
         this.commitMessage = data.project.mergeRequest.defaultMergeCommitMessage;
         this.squashBeforeMerge = data.project.mergeRequest.squashOnMerge;
         this.isSquashReadOnly = data.project.squashReadOnly;

app/assets/javascripts/vue_merge_request_widget/queries/states/ready_to_merge.fragment.graphql

@@ -5,6 +5,7 @@ fragment ReadyToMerge on Project {
   mergeRequest(iid: $iid) {
     autoMergeEnabled
     shouldRemoveSourceBranch
+    forceRemoveSourceBranch
     defaultMergeCommitMessage
     defaultMergeCommitMessageWithDescription
     defaultSquashCommitMessage