drop deprecated @platformName and @platformStatic annotations

compiler/testData/codegen/boxWithStdlib/reflection/call/returnUnit.kt

@@ -7,7 +7,7 @@ class A {
 }
 
 object O {
-    @kotlin.platform.platformStatic fun baz() {}
+    @JvmStatic fun baz() {}
 }
 
 fun nullableUnit(unit: Boolean): Unit? = if (unit) Unit else null

compiler/testData/codegen/boxWithStdlib/reflection/genericSignature/kt6106.kt

@@ -1,13 +1,11 @@
 package test
 
-import kotlin.platform.platformStatic
-
 open class B
 
 class A {
 
     companion object {
-        @platformStatic
+        @JvmStatic
         fun <T: B> a(s: T) : T {
             return s
         }