Minor: fix test data

dummy.kt was added for Gradle test (it does not start otherwise).
Old IC recompiles this file, so new and old IC logs are different.

jps-plugin/testData/incremental/pureKotlin/multifileClassRemoved/build.log

@@ -10,5 +10,14 @@ Cleaning output files:
 End of files
 Compiling files:
 End of files
-Exit code: OK
+Exit code: ADDITIONAL_PASS_REQUIRED
 ------------------------------------------
+Cleaning output files:
+  out/production/module/META-INF/module.kotlin_module
+  out/production/module/foo/DummyKt.class
+End of files
+Compiling files:
+  src/dummy.kt
+End of files
+Exit code: OK
+------------------------------------------

jps-plugin/testData/incremental/pureKotlin/multifileClassRemoved/experimental-ic-build.log

@@ -0,0 +1,14 @@
+================ Step #1 =================
+
+Cleaning output files:
+  out/production/module/META-INF/module.kotlin_module
+  out/production/module/test/Test.class
+  out/production/module/test/Test__AKt.class
+End of files
+Cleaning output files:
+  out/production/module/test/Test__BKt.class
+End of files
+Compiling files:
+End of files
+Exit code: OK
+------------------------------------------