Fix includes and requisites

[rhansen]

PR progress checklist (to be filled in by reviewers)

• [ ] Changes to documentation are appropriate (or tick if not required)
• [ ] Changes to tests are appropriate (or tick if not required)
• [ ] Reviews completed

---

What type of PR is this?

Primary type

• [ ] [build] Changes related to the build system
• [ ] [chore] Changes to the build process or auxiliary tools and libraries such as documentation generation
• [ ] [ci] Changes to the continuous integration configuration
• [ ] [feat] A new feature
• [x] [fix] A bug fix
• [ ] [perf] A code change that improves performance
• [ ] [refactor] A code change that neither fixes a bug nor adds a feature
• [ ] [revert] A change used to revert a previous commit
• [ ] [style] Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc.)

Secondary type

• [ ] [docs] Documentation changes
• [ ] [test] Adding missing or correcting existing tests

Does this PR introduce a BREAKING CHANGE?

No.

Related issues and/or pull requests

None.

Describe the changes you're proposing

This PR fixes a few problems with requisites:

• If letsencrypt.install_method != 'package', the create-initial-cert-*-* state did not have a dependency (direct or indirect) on the certbot utility, causing failure on a fresh system.
• The letsencrypt-config state was missing a dependency on letsencrypt-config-directory.
• The requisites for the cron job state are unnecessary when removing the cron job.

• Applying the letsencrypt.domains state would trigger errors due to missing includes:

  $ salt domain.example.com state.apply letsencrypt.domains
  ...
  ----------
            ID: create-initial-cert-domain.example.com-domain.example.com
      Function: cmd.run
          Name: /usr/bin/certbot certonly \
    --quiet \
    --non-interactive \
    --authenticator nginx \
    --installer nginx \
    --cert-name domain.example.com \
    -d domain.example.com
  
        Result: False
       Comment: The following requisites were not found:
                                   require:
                                       pkg: letsencrypt-client
                                       file: letsencrypt-config
       Started: 20:28:25.859877
      Duration: 0.018 ms
       Changes:
  ----------
            ID: letsencrypt-crontab-domain.example.com-domain.example.com
      Function: cron.absent
          Name: /usr/bin/certbot renew domain.example.com
        Result: False
       Comment: The following requisites were not found:
                                   require:
                                       pkg: letsencrypt-client
       Started: 20:28:25.863317
      Duration: 0.006 ms
       Changes:
  ...

Pillar / config required to test the proposed changes

Debug log showing how the proposed changes work

Documentation checklist

• [ ] Updated the README (e.g. Available states).
• [ ] Updated pillar.example.

Testing checklist

• [ ] Included in Kitchen (i.e. under state_top).
• [ ] Covered by new/existing tests (e.g. InSpec, Serverspec, etc.).
• [ ] Updated the relevant test pillar.

Additional context