Tiny touchups for deps, clean

[jtcohen6]

Resolved teensy bugs uncovered during the bug bash!

Avoid deprecation warning if irrelevant

This is a reasonable thing many users will do:

• finding out that dbt_modules has been renamed to dbt_packages
• adding dbt_packages to clean-targets (but leaving dbt_modules in there still)

Let's consider the deprecation warning "addressed" by that change, and stop raising it. Alternatively, if they do want to keep using dbt_modules and configure packages-install-path: "dbt_modules", we shouldn't raise the warning.

Use actual (bad) profile name

dbt clean + dbt deps are supposed to work even with an invalid database connection (profile). One easy way to test this is by running with, e.g., dbt clean --profile badprof.

@joellabes and I noticed that dbt uses the profile name specified in dbt_project.yml instead of the one specified in the CLI arg:

$ dbt clean --profile bad
18:22:44 | [ info  ] | Running with dbt=1.0.0-rc3
18:22:44 | [ info  ] | No profile "garage-postgres" found, continuing with no target

This PR would have us use Profile.pick_profile_name to find the right profile name for the log message. Voila:

$ dbt clean --profile bad
18:29:02 | [ info  ] | Running with dbt=1.0.0-rc2
18:29:03 | [ info  ] | No profile "bad" found, continuing with no target