[TEST] Migrate AbstractDiagnosticsWithExplicitApi to new test runners

compiler/tests-common/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsWithExplicitApi.kt

@@ -1,19 +0,0 @@
-/*
- * Copyright 2010-2019 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.checkers
-
-import org.jetbrains.kotlin.config.*
-import org.jetbrains.kotlin.test.ConfigurationKind
-
-abstract class AbstractDiagnosticsWithExplicitApi : AbstractDiagnosticsTest() {
-    override fun defaultLanguageVersionSettings(): LanguageVersionSettings =
-        CompilerTestLanguageVersionSettings(
-            DEFAULT_DIAGNOSTIC_TESTS_FEATURES,
-            LanguageVersionSettingsImpl.DEFAULT.apiVersion,
-            LanguageVersionSettingsImpl.DEFAULT.languageVersion,
-            mapOf(AnalysisFlags.explicitApiMode to ExplicitApiMode.STRICT)
-        )
-}