What should I say if I got promoted for dropping code quality to meet deadlines?

wear the shame proudly.

in 10 years you will have moved up several steps on the ladder using this technique. and probably earned a good salary.

the dept you lead is in constant turmoil, no long term planning is done, the code is brittle and un-understandable and un-changeable, but somehow enough fires are put out for things to almost work.

all caused by you doing something 'quick and dirty', being rewarded for it. and this becoming an example that others follow.

welcome to 95% of the world.