Run smoke tests only on java 11 (#1247)

smoke-tests/smoke-tests.gradle

@@ -1,3 +1,11 @@
+ext {
+  // we only need to run the Spock test itself under a single Java version, and the Spock test in
+  // turn is parameterized and runs the test using different docker containers that run different
+  // Java versions
+  minJavaVersionForTests = JavaVersion.VERSION_11
+  maxJavaVersionForTests = JavaVersion.VERSION_11
+}
+
 apply from: "$rootDir/gradle/java.gradle"
 
 description = 'smoke-tests'
@@ -20,4 +28,4 @@ test {
   doFirst {
     jvmArgs "-Dio.opentelemetry.smoketest.agent.shadowJar.path=${project(':javaagent').tasks.shadowJar.archivePath}"
   }
-}
+}