By George SolomonFROM the moment Goo Goo Dolls made the bold decision to walk out to Pink Floyd at Rock City on Tuesday night, there was a feeling that it would be all downhill from there.And, sadly, it was.How a band who have been together for 28 years can still all but fill Rock City despite the fact that they appear to have just one song to really get the crowd going is astounding.Iris, comfortably their best known tune, is saved for late on in the set and the whole night feels like a build up to it.When they played Slide, arguably their second best song, early on, the female