Signed-off-by: Derek Nola <derek.nola@suse.com>

* Convert install tests to run PR version of k3s
Signed-off-by: Derek Nola <derek.nola@suse.com>

Signed-off-by: Derek Nola <derek.nola@suse.com>

* Replace CentOS 8 with Rocky 8 for install testing
Signed-off-by: Derek Nola <derek.nola@suse.com>

* Removed vagrant folder
* Fix comments around E2E ENVs
* Eliminate testutil folder
* Convert flock integration test to unit test
* Point to other READMEs
Signed-off-by: Derek Nola <derek.nola@suse.com>

- updated `tests/TESTING.md`
- cgroup, snapshotter, and install tests all under tests/vagrant
- cgroup and snapshotter workflows trigger for all code changes on all branches (excluding markdown docs, install script, and other vagrant tests)
- install workflow triggers for relevant script and fixture changes, only on master or pull-requests that target it
- integration and unit test workflows should not trigger for install script changes nor anything under tests/vagrant
Signed-off-by: Jacob Blain Christen <jacob@rancher.com>

- also updated k3s-uninstall.sh on zypper and TU systems
- fix #4409 for Fedora CoreOS

new installer tests via github actions:
- fedora-coreos
- opensuse-microos
Signed-off-by: Jacob Blain Christen <jacob@rancher.com>

Support invoking install.sh on SLE Micro with or without SELinux
enabled. Same deal for SLES.

Additionally, easy-to-invoke assertions, via Vagrant, that the local
install.sh works correctly:
- tests/install/centos-7 (stand-in for rhel 7)
- tests/install/centos-8 (stand-in for rhel 8)
- tests/install/opensuse-leap (stand-in for sles)
- tests/install/opensuse-microos (stand-in for sle-micro)
- tests/install/ubuntu-focal

Addresses #3188
Addresses #3917
Signed-off-by: Jacob Blain Christen <jacob@rancher.com>