Remove PostgREST (#41299)

This PR removes the PostgREST containers and deployments, as we're no
longer using it.

Release Notes:

- N/A

script/deploy-postgrest

@@ -1,20 +0,0 @@
-#!/usr/bin/env bash
-
-set -eu
-source script/lib/deploy-helpers.sh
-
-if [[ $# != 1 ]]; then
-  echo "Usage: $0 <production|staging> (postgrest not needed on preview or nightly)"
-  exit 1
-fi
-environment=$1
-
-export_vars_for_environment ${environment}
-
-export ZED_DO_CERTIFICATE_ID=$(doctl compute certificate list --format ID --no-header)
-export ZED_KUBE_NAMESPACE=${environment}
-
-target_zed_kube_cluster
-envsubst < crates/collab/k8s/postgrest.template.yml | kubectl apply -f -
-
-echo "deployed postgrest"