test(run-engine): wait for the metrics emitter connection before exercising it

The emitter drops emissions until its Redis client is ready, and the
tests enqueued immediately after constructing it, so the first counter
entry was occasionally lost and the suite flaked roughly two runs in
eighty. Awaiting readiness makes every emission land.

Author: matt-aitken

internal-packages/run-engine/src/run-queue/metrics.test.ts

@@ -81,6 +81,7 @@ describe("RunQueue queue-metrics emission", () => {
       definition,
       flag: { enabled: () => true },
     });
+    await emitter.waitUntilReady();
 
     const queue = new RunQueue({
       name: "rq",
@@ -183,6 +184,7 @@ describe("RunQueue queue-metrics emission", () => {
         definition,
         flag: { enabled: () => true },
       });
+      await emitter.waitUntilReady();
       const queue = new RunQueue({
         name: "rq",
         tracer: trace.getTracer("rq"),
@@ -255,6 +257,7 @@ describe("RunQueue queue-metrics emission", () => {
       maxLen: 1000,
     };
     const emitter = new MetricsStreamEmitter({ redis, definition, flag: { enabled: () => true } });
+    await emitter.waitUntilReady();
     const queue = new RunQueue({
       name: "rq",
       tracer: trace.getTracer("rq"),
@@ -354,6 +357,7 @@ describe("RunQueue queue-metrics emission", () => {
       flag: { enabled: () => true },
       gaugeSampleRate: 0,
     });
+    await emitter.waitUntilReady();
     const queue = new RunQueue({
       name: "rq",
       tracer: trace.getTracer("rq"),