Remove Java formatting from build task in CI (#3507)

This saves time in CI spent performing the same source-level checks in
every build job. Checkstyle, PMD, and Spotless are now run once in the
"Lint and Format" job.

The -PskipPMD flag was replaced with a -PskipJavaFormat flag that
disables Checkstyle, PMD, and Spotless.

shared/java/javastyle.gradle

@@ -1,13 +1,12 @@
+if (!project.hasProperty('skipJavaFormat')) {
+    apply plugin: 'checkstyle'
 
-apply plugin: 'checkstyle'
+    checkstyle {
+        toolVersion = "8.38"
+        configDirectory = file("${project.rootDir}/styleguide")
+        config = resources.text.fromFile(new File(configDirectory.get().getAsFile(), "checkstyle.xml"))
+    }
 
-checkstyle {
-    toolVersion = "8.38"
-    configDirectory = file("${project.rootDir}/styleguide")
-    config = resources.text.fromFile(new File(configDirectory.get().getAsFile(), "checkstyle.xml"))
-}
-
-if (!project.hasProperty('skipPMD')) {
     apply plugin: 'pmd'
 
     pmd {