Remove leftovers of platformName and platformStatic in test data

Drop unnecessary imports, rename some tests

idea/testData/checker/JvmStaticUsagesRuntime.kt

@@ -1,5 +1,3 @@
-import kotlin.jvm.JvmStatic
-
 <error descr="[WRONG_ANNOTATION_TARGET] This annotation is not applicable to target 'class'">@JvmStatic</error>
 class A {
     <error descr="[WRONG_ANNOTATION_TARGET] This annotation is not applicable to target 'companion object'">@JvmStatic</error>

idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevelMultifileRuntime.kt

@@ -2,12 +2,9 @@
 @file:JvmMultifileClass
 package test
 
-import kotlin.jvm.JvmName
-import kotlin.jvm.JvmMultifileClass
-
 <error descr="[CONFLICTING_JVM_DECLARATIONS] Platform declaration clash: The following declarations have the same JVM signature (getX()I):
     fun <get-x>(): Int
     fun getX(): Int">val x</error> = 1
 <error descr="[CONFLICTING_JVM_DECLARATIONS] Platform declaration clash: The following declarations have the same JVM signature (getX()I):
     fun <get-x>(): Int
-    fun getX(): Int">fun getX()</error> = 1
+    fun getX(): Int">fun getX()</error> = 1