testing-env: create default atlantis user

[nitrocode]

what

• testing-env: create default atlantis user

why

• Running tests on the testing-env fail because the negative tests create files that root can see and modify. However, if anyone runs the tests locally, in non-root, it passes fine.
• This issue only seems to affect the new golang 1.19 image and not the previous golang 1.17 image
• Approving and merging this will create a new testing-env image which can be set in our github workflow and circleci to allow bumping dependencies that require modern versions of golang.

references

• Affects PR upgrade Git clone locking mechanism to go1.19 #2521
• Affects PR upgrade Git clone locking mechanism to go1.19 #2521
• https://snyk.io/blog/containerizing-go-applications-with-docker/

commands

This command fails to run tests

$ docker run -it \
  -w /atlantis \
  -v $(pwd):/atlantis \
  ghcr.io/runatlantis/testing-env:2022.11.13 \
  sh -c "make test"

I built a local container and ran the tests using the atlantis user

$ docker build -t testing-env testing/
$ docker run -it \
  -w /atlantis \
  -v $(pwd):/atlantis \
  testing-env \
  sh -c "make test"
...
ok  	github.com/runatlantis/atlantis/server/events/vcs	8.845s
ok  	github.com/runatlantis/atlantis/server/events/vcs/bitbucketcloud	0.037s
ok  	github.com/runatlantis/atlantis/server/events/vcs/bitbucketserver	0.046s
ok  	github.com/runatlantis/atlantis/server/events/vcs/common	0.023s
?   	github.com/runatlantis/atlantis/server/events/vcs/fixtures	[no test files]
ok  	github.com/runatlantis/atlantis/server/events/webhooks	0.010s
ok  	github.com/runatlantis/atlantis/server/jobs	0.029s
ok  	github.com/runatlantis/atlantis/server/logging	0.034s
?   	github.com/runatlantis/atlantis/server/metrics	[no test files]
ok  	github.com/runatlantis/atlantis/server/recovery	0.004s [no tests to run]
?   	github.com/runatlantis/atlantis/server/scheduled	[no test files]
?   	github.com/runatlantis/atlantis/testdrive	[no test files]