use otel for observability (#635)

## Description:

## Please complete the following:

- [ ] I have added screenshots for all UI updates
- [ ] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [ ] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

<DISCORD USERNAME>

Co-authored-by: evan <openfrontio@gmail.com>

src/server/Master.ts

@@ -11,7 +11,7 @@ import { generateID } from "../core/Util";
 import { gatekeeper, LimiterType } from "./Gatekeeper";
 import { logger } from "./Logger";
 import { MapPlaylist } from "./MapPlaylist";
-import { setupMetricsServer } from "./MasterMetrics";
+import { setupMasterMetrics } from "./MasterMetrics";
 
 const config = getServerConfigFromServer();
 const playlist = new MapPlaylist();
@@ -20,12 +20,13 @@ const readyWorkers = new Set();
 const app = express();
 const server = http.createServer(app);
 
-// Create a separate metrics server on port 9090
-const metricsApp = express();
-const metricsServer = http.createServer(metricsApp);
-
 const log = logger.child({ comp: "m" });
 
+if (config.otelEnabled()) {
+  console.log("setting up master metrics");
+  setupMasterMetrics();
+}
+
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
 app.use(express.json());
@@ -146,9 +147,6 @@ export async function startMaster() {
   server.listen(PORT, () => {
     log.info(`Master HTTP server listening on port ${PORT}`);
   });
-
-  // Setup the metrics server
-  setupMetricsServer();
 }
 
 app.get(