Fix testNoMasterActionsWriteMasterBlock (#42798)

This commit performs the proper restore of network disruption.
Previously disruptionScheme.stopDisrupting() was called that does not
ensure that connectivity between cluster nodes is restored. The test
was checking that the cluster has green status, but it was not checking
that connectivity between nodes is restored.
Here we switch to internalCluster().clearDisruptionScheme(true) which
performs both checks before returning.

Closes #39688

(cherry picked from commit c8988d5)

server/src/test/java/org/elasticsearch/cluster/NoMasterNodeIT.java

@@ -192,7 +192,6 @@ void checkWriteAction(ActionRequestBuilder<?, ?> builder) {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/39688")
     public void testNoMasterActionsWriteMasterBlock() throws Exception {
         Settings settings = Settings.builder()
             .put(AutoCreateIndex.AUTO_CREATE_INDEX_SETTING.getKey(), false)
@@ -264,8 +263,6 @@ public void testNoMasterActionsWriteMasterBlock() throws Exception {
             assertThat(e.status(), equalTo(RestStatus.SERVICE_UNAVAILABLE));
         }
 
-        disruptionScheme.stopDisrupting();
-
-        client().admin().cluster().prepareHealth().setWaitForGreenStatus().setWaitForNodes("3").get();
+        internalCluster().clearDisruptionScheme(true);
     }
 }