OAuth redirect post-login is broken on k8s

Created by: ryphil

Steps to reproduce:

• Log out
• Click on a link to k8s, like https://k8s.sgdev.org/search?q=context:global+test+oauth&patternType=literal
• Be redirected to login
• Choose gsuite
• after the auth flow completes, you land on https://k8s.sgdev.org/, not https://k8s.sgdev.org/search?q=context:global+test+oauth&patternType=literal

For the logout “bug”: (not what I meant to report here but really annoying regardless)

• Go to a page that uses polling so it does requests frequently and leave it open in the background for an hour or so https://k8s.sgdev.org/users/jeff.wayman/batch-changes/deploy-docs-link-updates
• Come back, you should be logged out, although the page does frequent requests

Reported via Slack: https://sourcegraph.slack.com/archives/C03CSAER9LK/p1651860586880299