Remove leftovers of platformName and platformStatic in test data

Drop unnecessary imports, rename some tests

compiler/testData/compileJavaAgainstKotlin/jvmStatic/simpleCompanionObject.txt

@@ -0,0 +1,23 @@
+package test
+
+public fun main(/*0*/ kotlin.Array<kotlin.String>): kotlin.Unit
+
+public final class A {
+    public constructor A()
+
+    public companion object Companion {
+        private constructor Companion()
+        public final val b: kotlin.String
+        @kotlin.jvm.JvmStatic() public final fun test1(): kotlin.Unit
+        @kotlin.jvm.JvmStatic() public final fun test2(): kotlin.Unit
+        public final fun test3(): kotlin.Unit
+        @kotlin.jvm.JvmStatic() public final fun kotlin.String.test4(): kotlin.Unit
+    }
+}
+
+public/*package*/ open class Test {
+    public/*package*/ constructor Test()
+
+    // Static members
+    public open fun main(/*0*/ kotlin.Array<(out) kotlin.String!>!): kotlin.Unit
+}