make jps-plugin testable from IJ infrastructure

^KTIJ-20456

jps/jps-plugin/src/org/jetbrains/kotlin/jps/build/KotlinBuilder.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.jps.build
@@ -636,11 +625,11 @@ class KotlinBuilder : ModuleLevelBuilder(BuilderCategory.SOURCE_PROCESSOR) {
     // When JPS is run on TeamCity, it can not rely on Kotlin plugin layout,
     // so the path to Kotlin is specified in a system property
     private fun computeKotlinPathsForJpsPlugin(messageCollector: MessageCollectorAdapter): KotlinPaths? {
-        if (System.getProperty("kotlin.jps.tests").equals("true", ignoreCase = true)) {
+        val jpsKotlinHome = System.getProperty(JPS_KOTLIN_HOME_PROPERTY)?.let { File(it) }
+        if (System.getProperty("kotlin.jps.tests").equals("true", ignoreCase = true) && jpsKotlinHome == null) {
             return PathUtil.kotlinPathsForDistDirectory
         }
 
-        val jpsKotlinHome = System.getProperty(JPS_KOTLIN_HOME_PROPERTY)?.let { File(it) }
         return when {
             jpsKotlinHome == null -> {
                 messageCollector.report(ERROR, "Make sure that '$JPS_KOTLIN_HOME_PROPERTY' system property is set in JPS process")