fix: Remove forcing of groovy-xml (#281)

This configuration is no longer necessary as
the groovy-xml version no longer leaks from
the gradle-gradle-plugin (via grails-bootstrap
and grails-shell).

Related: grails/grails-gradle-plugin#273

grails-forge-core/src/main/java/org/grails/forge/feature/build/gradle/templates/buildSrcBuildGradle.rocker.raw

@@ -21,10 +21,4 @@ dependencies {
     @dependency.toSnippet()
 }
 }
-}
-
-configurations.configureEach {
-    // Needed for Gradle compatibility with Grails Gradle Plugin.
-    // (Only needed when there are files in buildSrc/src/*/groovy)
-    resolutionStrategy.force "org.codehaus.groovy:groovy-xml:${GroovySystem.version}"
 }