Keep gwt-user and gwt-dev off the test classpath

The previous refactor moved gwt-user, gwt-dev and gwt-servlet from compileOnly to library(), which adds dependencies to both compileOnly and testImplementation. That dragged gwt-dev's uber-jar onto the test classpath, where its bundled (old) copy of org.apache.commons.io.IOUtils took precedence over the resolved commons-io 2.22.0, breaking testcontainers' shaded docker-java client (NoSuchMethodError on IOUtils.toString(InputStream, Charset)).

Restore the pre-refactor split: gwt-user and gwt-dev are compileOnly, only gwt-servlet uses library() since it's also needed at test runtime. dependencySubstitution still rewrites all three coordinates in latest-deps mode, and the broadened compileClasspath pinning keeps the substituted artifacts pinned.

Author: trask

instrumentation/gwt-2.0/javaagent/build.gradle.kts

@@ -44,8 +44,9 @@ if (otelProps.testLatestDeps) {
 
 dependencies {
   // these are needed for compileGwt task
-  library("com.google.gwt:gwt-user:2.0.0")
-  library("com.google.gwt:gwt-dev:2.0.0")
+  compileOnly("com.google.gwt:gwt-user:2.0.0")
+  compileOnly("com.google.gwt:gwt-dev:2.0.0")
+  // gwt-servlet is also needed at test runtime
   library("com.google.gwt:gwt-servlet:2.0.0")
 
   testInstrumentation(project(":instrumentation:servlet:servlet-3.0:javaagent"))