Minor: replace UsefulTestCase with KtUsefulTestCase

For some reason assertSameLinesWithFile from UsefulTestCase
fails with exception on TeamCity, whereas the one KtUsefulTestCase
does not

plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/AbstractJvmAbiContentTest.kt

@@ -1,9 +1,9 @@
 package org.jetbrains.kotlin.jvm.abi
 
-import com.intellij.testFramework.UsefulTestCase
 import org.jetbrains.kotlin.codegen.BytecodeListingTextCollectingVisitor
 import org.jetbrains.kotlin.incremental.isClassFile
 import org.jetbrains.kotlin.jvm.abi.asm.ABI_EXTENSION_ASM_API_VERSION
+import org.jetbrains.kotlin.test.testFramework.KtUsefulTestCase
 import org.jetbrains.org.objectweb.asm.*
 import java.io.File
 
@@ -34,6 +34,6 @@ abstract class AbstractJvmAbiContentTest : BaseJvmAbiTest() {
         if (!signaturesFile.exists()) {
             signaturesFile.writeText("")
         }
-        UsefulTestCase.assertSameLinesWithFile(signaturesFile.canonicalPath, actual)
+        KtUsefulTestCase.assertSameLinesWithFile(signaturesFile.canonicalPath, actual)
     }
 }