Stabilize api_user password on PR apps

[chiaberry]

We have different build passwords for review, staging and production. The passwords are set when the branches are created, however when updating a review app's db to match production's the api_user password gets overwritten, which leads to publisher errors. This will also happen next time we push prod data to staging

One solution is to somehow set it so the api_user's information isnt overwritten. We wouldnt be able to run the simple copy command on Heroku

Another solution is to set, if only in the interim, all of the passwords to be the same until we are able to figure out a solution with copying databases.