Move credentials and discovery to edxlocal for database setup

[cpennington]

N.B. This may break docker-based devstacks. Fix TBD.

@maxrothman, @jimabramson, @zubair-arbi: I think this will fix the current credentials issues.

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[maxrothman]

This should also remove CREDENTIALS_MYSQL_MATCHER, CREDENTIALS_DB_ADMIN_PASSWORD, CREDENTIALS_DB_ADMIN_USER, and any similar vars from credentials/defaults/main.yml (and maybe discovery too?)

[cpennington]

We're likely to need them for making docker work, but I can remove them as well, to keep the changes in a single commit.

[maxrothman]

👍

[maxrothman]

@zubair-arbi you should rebase your branch on top of this one. (alternatively @jimabramson)

[cpennington]

@maxrothman or we can merge it to master, or to @zubair-arbi's branch.

[cpennington]

I'm going to squash this

[jimabramson]

@cpennington thanks for this. 👍 @maxrothman would it make sense to merge this to master and then rebase #2781 ?

[maxrothman]

@jimabramson you can rebase on this branch, and when it eventually makes it to master it'll effectively be the same thing.

[jimabramson]

@maxrothman ok.

[jimabramson]

these commits got merged directly into #2781