Fix(pg:promote): pg:promote returns early and does not promote when no database name DATABASE exists.

[justinwilaby]

This PR fixes a regression defect caused by an early return statement. When no current database was found, the entire command would return causing the database to not be promoted and no message given to the user.

To Test

1. Checkout this branch and build
2. Add 2 Heroku PG databases and then delete the first one. (this is a shortcut to remove the DATABASE attachment
3. Confirm no DATABSE attachment exists
4. execute the command bin/run pg:promote <postgresql_databse_name> -a <app_name>
5. Verify the output includes pg:promote succeeded.

tickets
W-16645361
W-16615296

[eablack]

Hmm. I'm not 100% sure we're replicating the correct behavior. The "early return when it can't find DATABASE" logic was in place in 8.5.11 (https://github.com/heroku/cli/blob/v8.11.5/packages/pg-v5/commands/promote.js) and has been in place for a long time (as far back as 7.69.1 -- https://github.com/heroku/cli/blob/v7.69.1/packages/pg-v5/commands/promote.js). I'm not sure we're supposed to be creating a new database attachment when DATABASE doesn't exist. Can you check with the data team about the correct behavior here?