chore: Remove unused isNullOrEmpty import from ITUuidTest.java.

Author: gagangupt16

google-cloud-spanner/src/test/java/com/google/cloud/spanner/it/ITUuidTest.java

@@ -16,7 +16,6 @@
 
 package com.google.cloud.spanner.it;
 
-import static com.google.common.base.Strings.isNullOrEmpty;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;