[FLINK-6056] [build] Add rat exclude for 'tools/flink*'

This closes #3540

pom.xml

@@ -938,6 +938,7 @@ under the License.
 						<exclude>build-target/**</exclude>
 						<!-- Tools: watchdog -->
 						<exclude>tools/artifacts/**</exclude>
+						<exclude>tools/flink*/**</exclude>
 						<!-- PyCharm -->
 						<exclude>**/.idea/**</exclude>
 					</excludes>