move slack tools to their own subdomain so they don't conflict with the inviter redirect

[BenTheElder]

Should be easier to manage going forward, see:

• slack bots are down community#6841
• Switch slack.k8s.io to the community inviter link #4105

I spoke to katharine about reconfiguring the apps to point to this seperate domain, we can do that once this is deployed.

TODO (follow-up):

• actually delete deployed resources from Remove Slackin, as it is being bypassed #4112
• remove slackin from ingress config
• consider not tagging all apps slackin2 since that's not really accurate 🤷‍♂️

[dims]

/approve
/lgtm
/hold please remove hold when ready @BenTheElder

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: BenTheElder, dims

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[ameukam]

the certificate controller might not be able to create the certificate after the PR is merged. Safe approach is to deploy the DNS before the certificate.

/lgtm
/hold

Remove the hold when ready.

[BenTheElder]

I'll deploy DNS then let this merge, working on that now

[BenTheElder]

taking a bit, had to refresh myself on this first, dns push is running but pretty slowly ...

[BenTheElder]

DNS is live
/hold cancel