[tests] removed a ridiculously exotic feature that still works, but is too hard to test

Specifically, using as custom logger topic a concatenated string, like literally `"A" + "B"`. It works,
but depending on javac and phase of the moon that ends up as `"A" + "B"` or `"AB"`, and I don't
think it's worthwhile for lombok to try to be consistent in this and test for that.

test/transform/resource/before/LoggerSlf4j.java

@@ -28,7 +28,3 @@ class LoggerSlf4jWithStaticField {
 class LoggerSlf4jWithTwoStaticFields {
 	static final String TOPIC = "StaticField";
 }
-
-@Slf4j(topic="A"+"B")
-class LoggerSlf4jWithTwoLiterals {
-}