Move isolated addSuppressed extension test to jvm tests

Conditions for being isolated do not hold anymore:
it tested that addSuppressed extension could work without kotlin-stdlib-jdk7,
but now the latter is merged to kotlin-stdlib and thus always present

#KT-51907

libraries/stdlib/jdk7/build.gradle

@@ -17,11 +17,6 @@ sourceSets {
         kotlin {
         }
     }
-    noJdk7Test {
-        kotlin {
-            srcDir 'testNoJdk7'
-        }
-    }
     java9 {
         java {
             srcDir 'java9'
@@ -29,10 +24,6 @@ sourceSets {
     }
 }
 
-configurations {
-    noJdk7TestApi.extendsFrom(testApi)
-}
-
 dependencies {
     api project(':kotlin-stdlib')
     testApi project(':kotlin-test:kotlin-test-junit')
@@ -88,12 +79,4 @@ configureFrontendIr(project)
 
 LibrariesCommon.configureJava9Compilation(project, 'kotlin.stdlib.jdk7')
 
-task testNoJdk7(type: Test, dependsOn: noJdk7TestClasses) {
-    group = "verification"
-
-    testClassesDirs = sourceSets.noJdk7Test.output.classesDirs
-    classpath = sourceSets.noJdk7Test.runtimeClasspath
-}
-
-check.dependsOn testNoJdk7
 

libraries/stdlib/jdk7/testNoJdk7/ExceptionTest.kt

@@ -1,25 +0,0 @@
-/*
- * Copyright 2010-2020 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 test.exceptions
-
-import kotlin.addSuppressed as addSuppressedExtension
-import kotlin.test.*
-
-class ExceptionTest {
-
-    @Test
-    fun addSuppressedWorksWithoutJdk7Extensions() {
-        val e1 = Throwable()
-        val e2 = Exception("Suppressed")
-
-        assertTrue(e1.suppressedExceptions.isEmpty())
-        e1.addSuppressedExtension(e2)
-
-        assertSame(e2, e1.suppressed.singleOrNull())
-        assertSame(e2, e1.suppressedExceptions.singleOrNull())
-    }
-
-}

libraries/stdlib/jvm/test/exceptions/ExceptionJVMTest.kt

@@ -85,7 +85,19 @@ class ExceptionJVMTest {
     @Test
     fun addSuppressedSelfDoesNotThrow() {
         val e1 = Throwable()
-        e1.addSuppressed(e1) // should not throw
+        e1.addSuppressed(e1) // should not throw, extension hides member
+    }
+
+    @Test
+    fun addSuppressedWorksThroughExtension() {
+        val e1 = Throwable()
+        val e2 = Exception("Suppressed")
+
+        assertTrue(e1.suppressedExceptions.isEmpty())
+        e1.addSuppressed(e2)
+
+        assertSame(e2, e1.suppressed.singleOrNull())
+        assertSame(e2, e1.suppressedExceptions.singleOrNull())
     }
 
     @Test