[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/after-ecj/LoggerSlf4j.java

@@ -56,11 +56,3 @@ class LoggerSlf4jOuter {
     super();
   }
 }
-@Slf4j(topic = ExtendedStringLiteral{AB}) class LoggerSlf4jWithTwoLiterals {
-  private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger("AB");
-  <clinit>() {
-  }
-  LoggerSlf4jWithTwoLiterals() {
-    super();
-  }
-}