[misc] bump metrics module to 3.4.1

- renamed package from `metrics-sharelatex` to `@overleaf/metrics`
- drop support for statsd backend
- decaffeinate
- compress `/metrics` response using gzip
- bump debugging agents to latest versions
- expose prometheus interfaces for custom metrics (custom tags)
- cleanup of open sockets metrics
- fix deprecation warnings for header access

services/notifications/package.json

@@ -17,6 +17,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "@overleaf/metrics": "^3.4.1",
     "async": "^2.6.3",
     "body-parser": "^1.19.0",
     "coffee-script": "^1.12.7",
@@ -24,7 +25,6 @@
     "express": "4.17.1",
     "logger-sharelatex": "^2.2.0",
     "method-override": "^3.0.0",
-    "metrics-sharelatex": "^2.6.2",
     "mongodb": "^3.6.0",
     "node-statsd": "0.1.1",
     "request": "^2.88.2",