When the Goo Goo Dolls first got started, critics at the time accused them of being a cheap imitation of the Replacements, a band that amassed an underground following but never made it to the mainstream.And that may have been their destiny if John Rzeznik had never gotten over his shyness.  In fact, were it not for that, this weekend they might be playing a local club instead of headlining the Nikon at Jones Beach Theater in Wantagh this Sunday Night.Rzeznik's longtime band mate, bassist Robby Takac was the original lead singer and with their grungy sound at the time, it would have been