Filter patchset level drafts from drafts section in ReplyDialog

The patchset level comment is supposed to render at the top
in editing mode.
Given that the comment triggers a model update, it updates the
"draftCommentThreads" property in GrChangeView(righfully so) and
ends up being rendered twice in the reply dialog.
Hence explicitly filter out the patchset level thread from the
drafts container.

The solution works cleanly now as it is possible to only create
one patchset level draft per change.
If that changes in the future then this solution would need
to be adapted to ignore only the "latest" patchset level
comment but should be okay to adapt in the future.

Release-Notes: skip
Google-bug-id: b/242982372
Change-Id: I4005ec603c8e51930e9fafb1fb1f1a3e7259c0be

polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts

diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
index e99156d..015c205 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
@@ -687,7 +687,10 @@
     subscribe(
       this,
       () => this.getCommentsModel().draftThreads$,
-      threads => (this.draftCommentThreads = threads)
+      threads =>
+        (this.draftCommentThreads = threads.filter(
+          t => t.path !== SpecialFilePath.PATCHSET_LEVEL_COMMENTS
+        ))
     );
   }