Fix usages of any(<Primitive>.class) matchers (#4453)

In Mockito 2, if a method expects a primitive type, but an any(<Primitive>.class) matcher is used in its place, it will throw an error. To prepare for this upcoming breakage, change
all existing any(<Primitive>.class) matchers to use the correct any<Primitive>() matcher.

google-cloud-clients/google-cloud-spanner/src/test/java/com/google/cloud/spanner/BaseSessionPoolTest.java

@@ -17,6 +17,7 @@
 package com.google.cloud.spanner;
 
 import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.anyLong;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
@@ -45,8 +46,7 @@ public ScheduledExecutorService get() {
       // To prevent maintenance loop from running.
       doReturn(mockFuture)
           .when(mockExecutor)
-          .scheduleAtFixedRate(
-              any(Runnable.class), any(Long.class), any(Long.class), any(TimeUnit.class));
+          .scheduleAtFixedRate(any(Runnable.class), anyLong(), anyLong(), any(TimeUnit.class));
       return mockExecutor;
     }