Override level of apache error log in ossec config

[emkll]

Status

Ready for review

Description of Changes

Fixes #4339

Testing

1. Set up a production (VM or physical) SecureDrop instance
2. make build-debs on this branch
3. Go to Journalist Interface, click on Admin, navigate to Instance Config and click on "Send Test OSSEC Alert" button

• Observe no email received

4. copy securedrop-ossec-agent and ossec-agent debs to app server and install
5. copy securedrop-ossec-server and ossec-server debs to mon server and install
6. Go to Journalist Interface, click on Admin, navigate to Instance Config and click on "Send Test OSSEC Alert" button

• Observe email received

Deployment

New and existing SecureDrop instances will be upgraded via the securedrop-ossec-{client, server} deb packages.

Checklist

If you made changes to the system configuration:

• Configuration tests pass

If you made non-trivial code changes:

• I have written a test plan and validated it for this PR

[zenmonkeykstop]

Tested against a 0.12.1 NUC5 instance:

• Clicked SEND TEST OSSEC ALERT in admin section of JI, confirmed no email sent
• Ran make build-debs on branch, scped debs to app and mon, installed with dpkg
• Clicked SEND TEST OSSEC ALERT, confirmed email sent and decryptable with message:

[Mon Apr 15 20:50:41.624397 2019] [wsgi:error] [pid 4484:tid 3839274497792] ERROR:flask.app:This is a test OSSEC alert

👍

[redshiftzero]

approving based on @zenmonkeykstop testing, visual review of the diff looks good. thanks for the tests @emkll 🥇