ICU-23091 Fix plugin config

Author: echeran

icu4j/pom.xml

@@ -472,7 +472,7 @@
         <plugin>
           <groupId>com.diffplug.spotless</groupId>
           <artifactId>spotless-maven-plugin</artifactId>
-          <version>${spotless.version}</version>
+          <version>${formatter.plugin.spotless.version}</version>
           <configuration>
             <!-- optional: limit format enforcement to just the files changed by this feature branch -->
             <!-- You can explicitly disable ratchet functionality by providing the value 'NONE': -->