added functionality to load test data during staging provisioning

[zenmonkeykstop]

Status

Ready for review

Description of Changes

Fixes #5140 .

Adds option to provision a staging environment using instance data from a backup file.

Testing

Using an existing SecureDrop backup tarball (say, sd-backup.tar.gz):

• checkout this branch
• create a directory install_files/ansible-base/test-data and copy the backup file there.
• run make build-debs && make staging, verify that it completes successfully
• create an admin account, log into the JI, and verify that there are no sources or other journalist accounts on the instance
• run TEST_DATA_FILE="sd-backup.tar.gz" make staging and verify that it completes successfully
• verify that the SI and JI addresses remain unchanged from the initial run, and have not been set to those in the backup tarball
• create an admin account, log into the JI, and verify that the sources and journalist accounts on the instance match those from the backup tarball
• verify that source login and submission, and journalist reply processes work correctly.

Deployment

Development/QA-only change

Checklist

If you made non-trivial code changes:

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

[emkll]

Thanks @zenmonkeykstop tested as follows using your test plan:

• checkout this branch
• create a directory install_files/ansible-base/test-data and copy the backup file there.
• run make build-debs && make staging, verify that it completes successfully
• create an admin account, log into the JI, and verify that there are no sources or other journalist accounts on the instance
• run TEST_DATA_FILE="sd-backup.tar.gz" make staging and verify that it completes successfully
• verify that the SI and JI addresses remain unchanged from the initial run, and have not been set to those in the backup tarball
• create an admin account, log into the JI, and verify that the sources and journalist accounts on the instance match those from the backup tarball
• verify that source login and submission, and journalist reply processes work correctly.
  Additional tests
• backup is properly gitignored

I ran into #4364 but it seems unrelated these changes.

I think prior to merge, it might be worth capturing the instructions from the test plan into some developer-facing docs? What do you think?

[zenmonkeykstop]

No problem! added in a description (and admonishment not to use data from a live instance for testing) in the development docs.

[conorsch]

Looks great. Full test plan passes locally. @emkll already asked for, and received, docs, so adding a +1 for merge.

CI failed on the updater gui tests, which is unrelated, so restarted the job.

[emkll]

CI is now passing, merging!