Removes unnecessary externalization of strings

ee/app/assets/javascripts/epic/components/epic_body.vue

@@ -70,7 +70,7 @@ export default {
       :allow-auto-complete="false"
       :path-id-separator="$options.epicsPathIdSeparator"
       :title="__('Epics')"
-      :issuable-type="__('epic')"
+      issuable-type="epic"
       css-class="js-related-epics-block"
     />
     <related-items
@@ -80,7 +80,7 @@ export default {
       :can-reorder="canAdmin"
       :allow-auto-complete="false"
       :title="__('Issues')"
-      :issuable-type="__('issue')"
+      issuable-type="issue"
       css-class="js-related-issues-block"
       path-id-separator="#"
     />

ee/changelogs/unreleased/kp-remove-unnecessary-string-externalization.yml

+---
+title: Fix the group's epic page. The Paste issue link placeholder shown as 'undefinedundefinedundefined'
+  in Chinese environment. And the error message showed nothing.
+merge_request: 16628
+author: wdmcheng
+type: fixed

locale/gitlab.pot

@@ -18577,9 +18577,6 @@ msgstr ""
 msgid "entries cannot contain HTML tags"
 msgstr ""
 
-msgid "epic"
-msgstr ""
-
 msgid "error"
 msgstr ""