[etcd-snapshot-restore] Snapshot/restore e2e test

[Danil-Grigorev]

What this PR does / why we need it:

Adds simple e2e scenario for performing ETCD snapshot and restore. Tests will run as nightly, which use EKS LB and allows to pull agent image from rancher without issues.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):

Fixes #502

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests

[Danil-Grigorev]

It appears the issue with the e2e setup is due to using isolated-kind ingress setup. While using sslip.io, RKE2 cluster fails to pull agent binary, even while running tests locally.

root@etcd-snapshot-restore-control-plane-pvqsg:/# sh opt/system-agent-install.sh 
[INFO]  CA strict verification is set to false
[INFO]  Using default agent configuration directory /etc/rancher/agent
[INFO]  Using default agent var directory /var/lib/rancher/agent
curl: (60) SSL certificate problem: unable to get local issuer certificate
More details here: https://curl.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

These tests are passing while using ngrok setup, which configures ingress for https access.