[Gradle, Test] Update kotlin-js-plugin-project with sources publication

Sources are published now as gradle variant, so it shouldn't be added
manually to publication.

^KT-36943

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-js-plugin-project/build.gradle.kts

@@ -51,7 +51,6 @@ publishing {
     publications {
         create("default", MavenPublication::class.java) {
             from(components.getByName("kotlin"))
-            artifact(tasks.getByName("kotlinSourcesJar"))
         }
     }
     repositories {