How to regenerate various sourcegraph.com tokens

`SRC_SESSION_COOKIE_KEY`

This can be regenerated by running:

> openssl rand -hex 16

Note: Existing users will be signed out, but they will be able to sign in again without any issues.

> openssl rand -base64 128

Needs to be updated in three places:

https://github.com/sourcegraph/infrastructure/blob/main/code-intel/terraform.tfvars
https://github.com/sourcegraph/deploy-sourcegraph-dot-com/blob/release/base/frontend/sourcegraph-frontend.Deployment.yaml
https://github.com/sourcegraph/deploy-sourcegraph-dot-com/blob/release/base/executor-queue/executor-queue.Deployment.yaml

Follow the instructions for deploying the terraform changes. The dot-com k8s changes are deployed as usual.