SI-8900 Don't assert !isDelambdafyFunction, it may not be accurate

The implementations of isAnonymousClass, isAnonymousFunction,
isDelambdafyFunction and isDefaultGetter check if a specific substring
(eg "$lambda") exists in the symbol's name.

SI-8900 shows an example where a class ends up with "$lambda" in its
name even though it's not a delambdafy lambda class. In this case the
conflict seems to be introduced by a macro. It is possible that the
compiler itself never introduces such names, but in any case, the
above methods should be implemented more robustly.

This commit is band-aid, it fixes one specific known issue, but there
are many calls to the mentioned methods across the compiler which
are potentially wrong.