HHH-13682 Remove unnecessary checks around Java 8 compatibility

The build requires JDK8+, so we're alwways Java 8 compatible.

documentation/documentation.gradle

@@ -139,10 +139,8 @@ task aggregateJavadocs(type: Javadoc) {
 			options.source = project.baselineJavaVersion
 		}
 
-		if ( JavaVersion.current().isJava8Compatible() ) {
 		options.addStringOption( 'Xdoclint:none', '-quiet' )
 	}
-	}
 
     // process each project, building up:
     //      1) appropriate sources

gradle/published-java-module.gradle

@@ -130,9 +130,7 @@ javadoc {
 			options.source = project.baselineJavaVersion
 		}
 
-		if ( JavaVersion.current().isJava8Compatible() ) {
 		options.addStringOption( 'Xdoclint:none', '-quiet' )
-		}
 
 		doFirst {
 			// ordering problems if we try to do this during config phase :(