use the pinned petclinic version in overhead tests. (#6306)

Author: breedx-splk

benchmark-overhead/src/test/java/io/opentelemetry/containers/PetClinicRestContainer.java

@@ -50,7 +50,7 @@ public GenericContainer<?> build() throws Exception {
     GenericContainer<?> container =
         new GenericContainer<>(
                 DockerImageName.parse(
-                    "ghcr.io/open-telemetry/opentelemetry-java-instrumentation/petclinic-rest-base:latest"))
+                    "ghcr.io/open-telemetry/opentelemetry-java-instrumentation/petclinic-rest-base:20220711201901"))
             .withNetwork(network)
             .withNetworkAliases("petclinic")
             .withLogConsumer(new Slf4jLogConsumer(logger))