Delete unused build script (#11294)

instrumentation/graphql-java/graphql-java-common/javaagent/build.gradle.kts

@@ -1,9 +0,0 @@
-plugins {
-  id("otel.javaagent-instrumentation")
-}
-
-dependencies {
-  implementation(project(":instrumentation:graphql-java:graphql-java-common:library"))
-
-  library("com.graphql-java:graphql-java:12.0")
-}