revert(scaling-dive): drop fanout-debounce lever entry (#103)

Scored against run 25940112728: this lever does not reduce emit
volume (the per-socket while-loop still emits one message per
revision per socket regardless of how many revs are batched into
one updatePadClients call). ether/etherpad#7766 closed.

Keep the 60-min timeout — that fix stands.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

.github/workflows/scaling-dive.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        lever: [baseline, websocket-only, nodemem, fanout-debounce]
+        lever: [baseline, websocket-only, nodemem]
 
     env:
       PNPM_HOME: /home/runner/setup-pnpm/node_modules/.bin
@@ -119,12 +119,6 @@ jobs:
               # No settings change; NODE_OPTIONS is set when launching below.
               echo "applied via NODE_OPTIONS"
               ;;
-            fanout-debounce)
-              # Lever 3: coalesce per-pad fan-out within a 50ms window
-              # (requires ether/etherpad#7766 in the checked-out core_ref).
-              sed -i '/"loadTest": true,/a\  "fanoutDebounceMs": 50,' settings.json
-              grep fanoutDebounceMs settings.json || { echo "fanoutDebounceMs not present — core must include #7766"; exit 1; }
-              ;;
             *)
               echo "unknown lever: ${{ matrix.lever }}" >&2
               exit 1