We never got a scene in any of the Trek shows or movies where thrusters would have been sufficient to get the ship from A to B. They can get the ship moving at a crawling pace, such as when piloting out of a spacedock. But if that's the best they can do, they would have to operate for months if not years to get the ship to another planet, through an asteroid belt, or whatnot.
IIRC in the very first episode of DS-9 the entire station was moved to it's new location by the wormhole by using it's thrusters. True O'Brian did some technobabble with the station's deflector shields to reduce it's mass, but it was also much larger than a Galaxy class ship and it traveled a considerable distance.
The destruction of the ancient ship was the worst thing aboutthis show for me. No reason for it- there have been hazards which needed to be studied (like the Dyson Sphere) and they did not have to destroy them after they escaped.