Prefer Kotlin Gradle test run configurations when possible (KT-33787)

idea/testData/gradle/testRunConfigurations/preferredConfigurations/build.gradle

@@ -0,0 +1,15 @@
+plugins {
+    id 'java'
+    id 'org.jetbrains.kotlin.jvm' version '1.3.50'
+}
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
+    testCompile "junit:junit:4.12"
+}

idea/testData/gradle/testRunConfigurations/preferredConfigurations/src/test/java/MyTest.java

@@ -0,0 +1,9 @@
+import org.junit.Test;
+
+public class MyTest {
+    @Test
+    public void testA() {}
+
+    @Test
+    public void testB() {}
+}

idea/testData/gradle/testRunConfigurations/preferredConfigurations/src/test/kotlin/MyKotlinTest.kt

@@ -0,0 +1,11 @@
+import org.junit.Test
+
+class MyKotlinTest {
+    @Test
+    fun testA() {
+    }
+
+    @Test
+    fun testB() {
+    }
+}