Fix MPP Gradle tests

* Use `maven { setUrl(...) }` in Groovy DSL
* Configure compilation tasks beforehand
  in testMppBuildWithCompilerPlugins
* Prevent `gradleSettingsScript()` from failing
  when no settings script is found

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/BaseGradleIT.kt

@@ -621,9 +621,11 @@ Finished executing task ':$taskName'|
         }.single()
 
     fun Project.gradleSettingsScript(): File =
-        listOf("settings.gradle", "settings.gradle.kts").mapNotNull {
+        listOf("settings.gradle", "settings.gradle.kts").map {
-            File(projectDir, it).takeIf(File::exists)
+            File(projectDir, it)
-        }.single()
+        }.run {
+            singleOrNull { it.exists() } ?: first()
+        }
 
     /**
      * @param assertionFileName path to xml with expected test results, relative to test resources root

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/NewMultiplatformIT.kt

@@ -1836,6 +1836,9 @@ class NewMultiplatformIT : BaseGradleIT() {
             noArg { annotation 'com.example.Annotation' }
 
             task $printOptionsTaskName {
+                // if the tasks are not configured during evaluation phase, configuring them during execution
+                // leads to new dependencies unsuccessfully added to the resolved compilerPluginsClasspath configuration
+                kotlin.targets.all { compilations.all { /*force to configure the*/ compileKotlinTask } }
                 doFirst {
                     kotlin.sourceSets.each { sourceSet ->
                         def args = sourceSet.languageSettings.compilerPluginArguments