Adapt mock build.gradle to get plugin from MavenCentral

reactor-tools/src/buildPluginTest/resources/mock-gradle/build.gradle

@@ -22,14 +22,18 @@ buildscript {
 		//the plugin feature only works with the -original jar !!
 		//otherwise implemented Plugin interface is the shaded one
 		classpath files("@AGENT@")
+		//version 1.12.13 cannot be found on Gradle Plugin Repository, this syntax allows looking it up on MavenCentral
+		classpath 'net.bytebuddy:byte-buddy-gradle-plugin:@BYTE_BUDDY_VERSION@'
 	}
 }
 
+
 plugins {
-	id "net.bytebuddy.byte-buddy-gradle-plugin" version "@BYTE_BUDDY_VERSION@"
 	id 'java'
 }
 
+apply plugin: "net.bytebuddy.byte-buddy-gradle-plugin"
+
 repositories {
 	mavenCentral()
 }