Fix GetToponymsByStreetcodeIdHandler

[PenultimateBoss]

GetToponymsByStreetcodeIdHandler.Handle method does not return Result.Fail when no toponyms are found.

According to IRepositoryBase interface, method GetAllAsync can`t return null, so check for null in if expression (line 34) is useless. Instead, better check if collection is empty.

Additional remarks:

1. Line 33 do basically nothing and partially copy logic of line 41. Suggest to just remove it;