PG: Remove legacy permission 'publishDrafts'

This was removed in 2.15 but was for some reason left in the FE.
Permission was removed with:

6ffb7d9358 Discontinue draft workflow

Change-Id: I21241f603bebe8b71ab0f9c4b98890d9d5d00bbc

polygerrit-ui/app/behaviors/gr-access-behavior/gr-access-behavior.html

@@ -88,10 +88,6 @@ limitations under the License.
             id: 'owner',
             name: 'Owner',
           },
-          publishDrafts: {
-            id: 'publishDrafts',
-            name: 'Publish Drafts',
-          },
           push: {
             id: 'push',
             name: 'Push',