Fix compile:android-test:generateAndroidTests

Don't read absent file with disabled plugins during creating Kotlin
core environment.

Exception in thread "main" java.lang.NullPointerException
	at java.io.Reader.<init>(Reader.java:78)
	at java.io.InputStreamReader.<init>(InputStreamReader.java:113)
	at com.intellij.ide.plugins.PluginManagerCore.readBrokenPluginFile(PluginManagerCore.java:249)
	at com.intellij.ide.plugins.PluginManagerCore.getBrokenPluginVersions(PluginManagerCore.java:241)
	at com.intellij.ide.plugins.PluginManagerCore.createLoadingResult(PluginManagerCore.java:822)
	at com.intellij.ide.plugins.DescriptorListLoadingContext.createSingleDescriptorContext(DescriptorListLoadingContext.java:64)
	at com.intellij.ide.plugins.PluginManagerCore.registerExtensionPointAndExtensions(PluginManagerCore.java:1318)
	at com.intellij.core.CoreApplicationEnvironment.registerExtensionPointAndExtensions(CoreApplicationEnvironment.java:287)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.registerApplicationExtensionPointsAndExtensionsFrom(KotlinCoreEnvironment.kt:622)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.createApplicationEnvironment(KotlinCoreEnvironment.kt:592)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.createForTests(KotlinCoreEnvironment.kt:505)
	at org.jetbrains.kotlin.android.tests.CodegenTestsOnAndroidGenerator$FilesWriter.writeFilesOnDisk(CodegenTestsOnAndroidGenerator.kt:214)
	at org.jetbrains.kotlin.android.tests.CodegenTestsOnAndroidGenerator$FilesWriter.writeFilesOnDiskIfNeeded(CodegenTestsOnAndroidGenerator.kt:208)

buildSrc/src/main/kotlin/CommonUtil.kt

@@ -59,6 +59,7 @@ fun Project.generator(fqName: String, sourceSet: SourceSet? = null, configure: J
     mainClass.set(fqName)
     workingDir = rootDir
     systemProperty("line.separator", "\n")
+    systemProperty("idea.ignore.disabled.plugins", "true")
     configure()
 }