VueJSMigration: Remove parallel-conflict-line component.

It's because Vue says: "Component template should contain exactly one root element".

app/assets/javascripts/merge_conflicts/components/parallel_conflict_line.js.es6

-/* eslint-disable */
-((global) => {
-
-  global.mergeConflicts = global.mergeConflicts || {};
-
-  global.mergeConflicts.parallelConflictLine = Vue.extend({
-    props: {
-      file: Object,
-      line: Object
-    },
-    mixins: [global.mergeConflicts.utils, global.mergeConflicts.actions],
-    template: '#parallel-conflict-line'
-  });
-
-})(window.gl || (window.gl = {}));

app/assets/javascripts/merge_conflicts/components/parallel_conflict_lines.js.es6

@@ -7,10 +7,7 @@
     props: {
       file: Object
     },
-    mixins: [global.mergeConflicts.utils],
-    components: {
-      'parallel-conflict-line': gl.mergeConflicts.parallelConflictLine
-    }
+    mixins: [global.mergeConflicts.utils, global.mergeConflicts.actions]
   });
 
 })(window.gl || (window.gl = {}));

app/views/projects/merge_requests/conflicts/components/_parallel_conflict_lines.html.haml

 %parallel-conflict-lines{"inline-template" => "true", ":file" => "file"}
   %table
     %tr.line_holder.parallel{"v-for" => "section in file.parallelLines"}
-      %td{"is"=>"parallel-conflict-line", "v-for" => "line in section", ":line" => "line", ":file" => "file"}
+      %template{"is"=>"parallel-conflict-line", "v-for" => "line in section", ":line" => "line", ":file" => "file"}
+        %td.diff-line-num.header{":class" => "lineCssClass(line)", "v-if" => "line.isHeader"}
+        %td.line_content.header{":class" => "lineCssClass(line)", "v-if" => "line.isHeader"}
+          %strong {{line.richText}}
+          %button.btn{"@click" => "handleSelected(file, line.id, line.section)"}
+            {{line.buttonTitle}}
+        %td.diff-line-num.old_line{":class" => "lineCssClass(line)", "v-if" => "!line.isHeader"}
+          {{line.lineNumber}}
+        %td.line_content.parallel{":class" => "lineCssClass(line)", "v-if" => "!line.isHeader", "v-html" => "line.richText"}
+