Fix IC test for multifile part with property

Our JPS and Gradle plugins handle
recompilation of multifile classes differently.

JPS plugin delegates handling to the JPS itself,
which tracks dependencies via bytecode,
and marks classes as dirty when they are affected.
So in JPS other parts of multifile classes are recompiled only
when a part's signature is changed.

In Gradle plugin we handle recompilation ourselves in
simpler way: any change in any part leads to a recompilation
of all parts of the same multifile class.

In future we should improve our Gradle plugin, but for now
I'm changing the test so that both JPS and Gradle tests
recompile all parts.

Also the dummy function is added to make sure that we
don't blindly recompile everything when a part is changed.

Original commit: 7f1d30058a

jps/jps-plugin/testData/incremental/withJava/other/multifilePartsWithProperties/build.log

@@ -9,4 +9,14 @@ Compiling files:
   src/partB.kt
 End of files
 Exit code: OK
+------------------------------------------
+Cleaning output files:
+  out/production/module/META-INF/module.kotlin_module
+  out/production/module/Utils.class
+  out/production/module/Utils__PartAKt.class
+End of files
+Compiling files:
+  src/partA.kt
+End of files
+Exit code: OK
 ------------------------------------------

jps/jps-plugin/testData/incremental/withJava/other/multifilePartsWithProperties/dummy.kt

@@ -0,0 +1 @@
+fun dummy() {}

jps/jps-plugin/testData/incremental/withJava/other/multifilePartsWithProperties/partB.kt.new.1

@@ -1,4 +1,4 @@
 @file:JvmName("Utils")
 @file:JvmMultifileClass
 
-val bVal: Int get() = 1
+val bVal: String get() = "1"