Delete unnecessary dummy module.

The comment says this module exists for testing purposes, but no tests fail without it. (Even if some did, they should arguably add it themselves.)

PiperOrigin-RevId: 869115712
Change-Id: Id90dea48583a12e218f7252bab90962aed14da62

Author: tjgq

src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java

@@ -1703,17 +1703,14 @@ public BlazeRuntime build() throws AbruptExitException {
 
       Preconditions.checkNotNull(clock);
 
-      int metricsModules = 0;
+      BlazeModule metricsModule = null;
       for (BlazeModule module : blazeModules) {
         if (module.postsBuildMetricsEvent()) {
-          metricsModules++;
+          checkState(metricsModule == null, "more than one module may post a BuildMetricsEvent");
+          metricsModule = module;
         }
       }
-      Preconditions.checkArgument(
-          metricsModules < 2, "At most one module may post a BuildMetricsEvent");
-      if (metricsModules == 0) {
-        blazeModules.add(new DummyMetricsModule());
-      }
+
       var blazeServicesCopy = ImmutableList.copyOf(blazeServices);
       for (BlazeModule module : blazeModules) {
         module.blazeServicesAvailable(blazeServicesCopy);

src/main/java/com/google/devtools/build/lib/runtime/DummyMetricsModule.java

@@ -344,8 +344,7 @@ public void returnsBothModulesAndServicesAsOptionsSuppliers() throws Exception {
 
     BlazeRuntime runtime = createRuntime(ImmutableList.of(module), ImmutableList.of(service));
 
-    // Additional modules may be registered internally, e.g. DummyMetricsModule.
-    assertThat(runtime.getOptionsSuppliers()).containsAtLeast(module, service);
+    assertThat(runtime.getOptionsSuppliers()).containsExactly(module, service);
   }
 
   private BlazeRuntime createRuntime() throws Exception {