MM-68047: Hide update status button in RHS post header

In the RHS (and smaller screens), the "Update your status" button
was consuming space that caused the username to be truncated or
hidden. Hide the button in the RHS context so the name remains
visible.

Made-with: Cursor

webapp/channels/src/sass/components/_post-right.scss

@@ -92,6 +92,15 @@
             }
         }
 
+        &.current--user {
+            &.other--root,
+            &.post--root {
+                .post__header-set-custom-status {
+                    display: none;
+                }
+            }
+        }
+
         &.post--comment {
             .post__body {
                 border-left: none;