Muzzle servlet-3 Instrumentation

Add muzzle block and remove class loader matcher method.

dd-java-agent/instrumentation/servlet-3/servlet-3.gradle

@@ -1,14 +1,10 @@
-apply plugin: 'version-scan'
-
-versionScan {
-  group = "javax.servlet"
-  module = 'javax.servlet-api'
-  legacyModule = "servlet-api"
-  versions = "[3.0,)"
-  verifyPresent = [
-    "javax.servlet.AsyncEvent"   : null,
-    "javax.servlet.AsyncListener": null,
-  ]
+muzzle {
+  pass {
+    group = "javax.servlet"
+    module = 'javax.servlet-api'
+    versions = "[3.0,)"
+    assertInverse = true
+  }
 }
 
 apply from: "${rootDir}/gradle/java.gradle"

dd-java-agent/instrumentation/servlet-3/src/main/java/datadog/trace/instrumentation/servlet3/AbstractServlet3Instrumentation.java

@@ -1,9 +1,6 @@
 package datadog.trace.instrumentation.servlet3;
 
-import static datadog.trace.agent.tooling.ClassLoaderMatcher.classLoaderHasClasses;
-
 import datadog.trace.agent.tooling.Instrumenter;
-import net.bytebuddy.matcher.ElementMatcher;
 
 public abstract class AbstractServlet3Instrumentation extends Instrumenter.Default {
 
@@ -11,11 +8,6 @@ public abstract class AbstractServlet3Instrumentation extends Instrumenter.Defau
     super("servlet", "servlet-3");
   }
 
-  @Override
-  public ElementMatcher<ClassLoader> classLoaderMatcher() {
-    return classLoaderHasClasses("javax.servlet.AsyncEvent", "javax.servlet.AsyncListener");
-  }
-
   @Override
   public String[] helperClassNames() {
     return new String[] {