Odds are, it was the battle bridge - elements of this TNG set were apparently used to create the guest starship bridges in DS9, and the Odyssey bridge indeed seems to be this generic guest starship bridge with an added railing and reshuffled chairs. Compare for example with the bridge elements of the Prometheus in "Second Sight", or of the Norkova in "The Passenger".
Odds also are, though, that the producers attempted to pass off the generic bridge as something close to the TNG Galaxy main bridge. Which would suggest that they wanted the real thing but couldn't get it, probably due to conflicting schedules.
After this, we for some reason stop seeing the guest starship bridge set. Instead, the "bridges" of the Lakota or the assorted ships contacting the Defiant during fleet action are shot using elements of the Defiant engineering set as the background. Apparently, the Defiant sets displaced the original guest bridge set...
Timo Saloniemi