Removes v2 service configuration and setup support

[zenmonkeykstop]

Status

Ready for review

Description of Changes

Closes #5731 .

• Removes the options to select v2 and/or v3 in sdconfig. v3 is the only option available, so no need to prompt.
• Removes ansible tasks and defaults related to v2 service setup, and cleans up conditionals around v3 config.
• Removes tailsconfig tasks and defaults related to v2 services.

Testing

Perform a from-scratch prod install with ssh-over-tor:

• Verify that you are not prompted to choose either v2 or v3 services during sdconfig
• Verify that the installation completes successfully
• Verify that tailsconfig completes successfully and only v3 desktops and ssh configs are created.
• Verify that v2 services are not defined on either server
• Verify backup/restore functionality

Perform a from-scratch prod install with ssh-over-lan:

• Verify that the cases above also pass with ssh-over-lan.

Run the install playbook against an existing 1.8.1 Focal instance:

• Verify that the installation completes successfully
• Verify that tailsconfig completes successfully and only v3 desktops and ssh configs are created.
• Verify that v2 services are not defined on either server

Deployment

Changes are deployed with admin workstation update (manual or GUI). In terms of server-side impact there should be no need for admin intervention or postint-style changes, as all new instances are v3-only anyway, and all instances must transition to Focal to remain accessible. The config files created by this branch are unchanged from those from a 1.8.0 or greater Focal install, with the exception of site-specific, which will now not contain the {v2,v3}_onion_services variables.

Checklist

If you made changes to the server application code:

• Linting (make lint) and tests (make test) pass in the development container

If you made changes to the system configuration:

• Configuration tests pass

If you added or removed a file deployed with the application:

• I have updated AppArmor rules to include the change

If you made non-trivial code changes:

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

Choose one of the following:

• I have opened a PR in the docs repo for these changes, or will do so later
• I would appreciate help with the documentation
• These changes do not require documentation

[codecov-commenter]

Codecov Report

Merging #5915 (a65bbd1) into develop (14c9d3a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #5915   +/-   ##
========================================
  Coverage    85.39%   85.39%           
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  Files           53       53           
  Lines         3904     3904           
  Branches       485      485           
========================================
  Hits          3334     3334           
  Misses         457      457           
  Partials       113      113           

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[emkll]

Thanks @zenmonkeykstop , changes LGTM, went through the test plan and visual review of the changes. I've opened freedomofpress/securedrop-docs#207 to track the documentation changes, which should be merged prior to releasing the changes introduced here.

[emkll]

these vars might linger in a site-specific file of existing instances, but since they are no longer used that should be fine