fix missing test suite definition for mongo-4.0

Author: jaydeluca

instrumentation/mongo/mongo-4.0/javaagent/build.gradle.kts

@@ -29,6 +29,20 @@ dependencies {
   testInstrumentation(project(":instrumentation:mongo:mongo-3.7:javaagent"))
 }
 
+testing {
+  suites {
+    val testStableSemconv by registering(JvmTestSuite::class) {
+      targets {
+        all {
+          testTask.configure {
+            jvmArgs("-Dotel.semconv-stability.opt-in=database")
+          }
+        }
+      }
+    }
+  }
+}
+
 tasks {
   withType<Test>().configureEach {
     usesService(gradle.sharedServices.registrations["testcontainersBuildService"].service)