Fix EE differences in parallel_diff_view.vue

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/10007

app/assets/javascripts/diffs/components/parallel_diff_view.vue

 <script>
 import { mapGetters } from 'vuex';
+import draftCommentsMixin from 'ee_else_ce/diffs/mixins/draft_comments';
 import parallelDiffTableRow from './parallel_diff_table_row.vue';
 import parallelDiffCommentRow from './parallel_diff_comment_row.vue';
 
-// eslint-disable-next-line import/order
-import ParallelDraftCommentRow from 'ee/batch_comments/components/parallel_draft_comment_row.vue';
-
 export default {
   components: {
     parallelDiffTableRow,
     parallelDiffCommentRow,
-    ParallelDraftCommentRow,
+    ParallelDraftCommentRow: () =>
+      import('ee_component/batch_comments/components/parallel_draft_comment_row.vue'),
   },
+  mixins: [draftCommentsMixin],
   props: {
     diffFile: {
       type: Object,
@@ -29,7 +29,6 @@ export default {
   },
   computed: {
     ...mapGetters('diffs', ['commitId']),
-    ...mapGetters('batchComments', ['shouldRenderParallelDraftRow', 'draftForLine']),
     diffLinesLength() {
       return this.diffLines.length;
     },

app/assets/javascripts/diffs/mixins/draft_comments.js

 export default {
   computed: {
     shouldRenderDraftRow: () => () => false,
+    shouldRenderParallelDraftRow: () => () => false,
     draftForLine: () => () => ({}),
   },
 };

ee/app/assets/javascripts/diffs/mixins/draft_comments.js

@@ -2,6 +2,10 @@ import { mapGetters } from 'vuex';
 
 export default {
   computed: {
-    ...mapGetters('batchComments', ['shouldRenderDraftRow', 'draftForLine']),
+    ...mapGetters('batchComments', [
+      'shouldRenderDraftRow',
+      'shouldRenderParallelDraftRow',
+      'draftForLine',
+    ]),
   },
 };