Skip spotless in release:prepare (#11285)

The weekly release of Jenkins 2.536 failed its initial build because Maven
release plugin 3.2.0 behaves differently than Maven release plugin 3.1.1.
For 2.535, we were using Maven release plugin 3.1.1 and it did not require
that we skip spotless verification during the `release:prepare` phase.
Maven release plugin 3.2.0 requires it.

Will allow the temporary change to be reverted from pull request:

* jenkins-infra/release#782

Special thanks to @jglick for noting the better way to resolve the issue.

Testing done:

* Confirmed that builds fail without this change when running

  `mvn -B -V -ntp release:prepare`

* Confirmed that builds pass with this change when running

  `mvn -B -V -ntp release:prepare`

Author: MarkEWaite

pom.xml

@@ -327,7 +327,7 @@ THE SOFTWARE.
         <!-- Version specified in parent POM -->
         <configuration>
           <!-- work around for a bug in javadoc plugin that causes the release to fail. see MRELEASE-271 -->
-          <preparationGoals>clean install</preparationGoals>
+          <preparationGoals>-Dspotless.check.skip clean install</preparationGoals>
           <goals>-DskipTests -Dspotbugs.skip -Dmaven.checkstyle.skip -Dspotless.check.skip generate-resources javadoc:javadoc deploy</goals>
           <pushChanges>false</pushChanges>
           <localCheckout>true</localCheckout>