fix: allow users to submit after editing (#46939)

If a user runs the tests and they pass, the multifile editor will show a
submit button.  If the user then edited the page, it would no longer be
possible to submit.

This ensures the redux store keeps the original, passing, tests and lets
the user submit

client/src/templates/Challenges/classic/editor.tsx

@@ -1084,7 +1084,10 @@ const Editor = (props: EditorProps): JSX.Element => {
       focusIfTargetEditor();
     }
 
-    if (props.initialTests) initTests(props.initialTests);
+    // Once a challenge has been completed, we don't want changes to the content
+    // to reset the tests since the user is already done with the challenge.
+    if (props.initialTests && !challengeIsComplete())
+      initTests(props.initialTests);
 
     if (hasEditableRegion() && editor) {
       if (props.isResetting) {