[Build] Avoid buildscript root capture into task action

#KT-44611 In Progress

libraries/tools/kotlin-gradle-plugin-idea-for-compatibility-tests/build.gradle.kts

@@ -25,9 +25,10 @@ val syncClasspath by tasks.register<Sync>("syncClasspath") {
     from(incomingClasspath)
     into(classpathDestination)
 
+    val testedVersionLocal = testedVersion
     /* Test if the correct version was resolved */
     doLast {
-        val expectedJar = destinationDir.resolve("kotlin-gradle-plugin-idea-$testedVersion.jar")
+        val expectedJar = destinationDir.resolve("kotlin-gradle-plugin-idea-$testedVersionLocal.jar")
         check(expectedJar.exists()) { "Expected $expectedJar in classpath. Found ${destinationDir.listFiles().orEmpty()}" }
     }
 }

libraries/tools/kotlin-gradle-plugin-idea/build.gradle.kts

@@ -47,8 +47,10 @@ run {
 
     tasks.test {
         dependsOnKotlinGradlePluginInstall()
-        inputs.files(compatibilityTestClasspath)
-        doFirst { systemProperty("compatibilityTestClasspath", compatibilityTestClasspath.files.joinToString(";") { it.absolutePath }) }
+        dependsOn(compatibilityTestClasspath)
+        val conf: FileCollection = compatibilityTestClasspath
+        inputs.files(conf)
+        doFirst { systemProperty("compatibilityTestClasspath", conf.files.joinToString(";") { it.absolutePath }) }
     }
 }