CI: Fix error when creating postgresql db
- [X] closes #29643

Not sure if this makes sense, but let's try if this is the problem.
Looks like this change adds this at the beginning of the log:
```
$ travis_setup_postgresql
Starting PostgreSQL v9.2
sudo service postgresql start 9.2
$ sudo service mysql start
start: Job is already running: mysql
```
But still the same error. I guess we'll have to add traces during the build to see if the postgres service is running, and what are the server, port... maybe if we used 9.5 instead of 9.2?  the log has a bit about shutting down 9.5, then starting 9.4 then stopping 9.4, then starting 9.3... Didn't see that, let's see if this works. I'm going to sleep now, feel free to push here if you want to try more things. Maybe someone from @travis-ci can help us here? I'm going to move the failing build to GitHub actions. That was more or less planned (#28545), and looks like shouldn't be difficult. let’s just disable the server for now
until it can be diagnosed
 > let’s just disable the server for now

Not sure what do you mean. Disable the failing build?

I guess if we temporary disable the creation of the db, and remove `psycopg2` from the dependencies, the CI will be green again, and just the postgres tests will be skipped.

But with some luck I can move the build to GitHub actions easily, and we can keep running the postgres tests, and have a permanent solution. I'll need #29661 merged soon for that. I think the problem is that something in https://github.com/pandas-dev/pandas/blob/master/ci/deps/travis-36-cov.yaml is making conda install postgres, see:
```
postgresql                11.2                 h20c2e04_0
```
I didn't see that there are two travis builds where the db is correctly created, and I think this is the main difference. In the working builds postgres is not installed.

Let's see if uninstalling coda fixes the error. @pandas-dev/pandas-core this fixes the problem with the CI (the postgresql error) great merge one green