Support Rocky Linux in node-join and agent/agentless installer scripts

[webvictim]

What would you like Teleport to do?

Support Rocky Linux (the "new CentOS") in Teleport installation scripts.

It's binary compatible with RHEL/CentOS, so checks like this can likely just have rocky added to the supported list:

• https://github.com/gravitational/teleport/blob/f06547a437fcdce389a75169b63998d2fe00d102/api/types/installers/agentless-installer.sh.tmpl#L149
• https://github.com/gravitational/teleport/blob/f06547a437fcdce389a75169b63998d2fe00d102/lib/web/scripts/node-join/install.sh#L926

What problem does this solve?

Enables easier installs on distros which are technically supported.

If a workaround exists, please include it.

Edit installer scripts yourself.

[zmb3]

@marcoandredinis is this good to close?

[marcoandredinis]

Yes, implemented in https://github.com/gravitational/teleport/pull/44283 and https://github.com/gravitational/teleport/pull/44319