Refactored InstrumentPlugin from Groovy to Kotlin.

Author: AlexeyKuznetsov-DD

buildSrc/build.gradle.kts

@@ -1,5 +1,4 @@
 plugins {
-  groovy
   `java-gradle-plugin`
   `kotlin-dsl`
   `jvm-test-suite`
@@ -16,7 +15,7 @@ gradlePlugin {
   plugins {
     create("instrument-plugin") {
       id = "dd-trace-java.instrument"
-      implementationClass = "InstrumentPlugin"
+      implementationClass = "datadog.gradle.plugin.instrument.InstrumentPlugin"
     }
     create("muzzle-plugin") {
       id = "dd-trace-java.muzzle"
@@ -55,7 +54,6 @@ repositories {
 
 dependencies {
   implementation(gradleApi())
-  implementation(localGroovy())
 
   implementation("net.bytebuddy", "byte-buddy-gradle-plugin", "1.18.1")