fix: update bitnami to use legacy image (#19891)

docs/install/kubernetes.md

@@ -46,6 +46,7 @@ on the internet that explain sensible configurations for this chart. Example:
 helm repo add bitnami https://charts.bitnami.com/bitnami
 helm install postgresql bitnami/postgresql \
     --namespace coder \
+    --set image.repository=bitnamilegacy/postgresql
     --set auth.username=coder \
     --set auth.password=coder \
     --set auth.database=coder \

docs/install/kubernetes/kubernetes-azure-app-gateway.md

@@ -109,6 +109,7 @@ The steps here follow the Microsoft tutorial for a Coder deployment.
    ```shell
    helm repo add bitnami https://charts.bitnami.com/bitnami
    helm install coder-db bitnami/postgresql \
+   --set image.repository=bitnamilegacy/postgresql
    --namespace coder \
    --set auth.username=coder \
    --set auth.password=coder \

docs/install/rancher.md

@@ -55,6 +55,7 @@ For proof-of-concept deployments, you can use Bitnami Helm chart to install Post
 ```console
 helm repo add bitnami https://charts.bitnami.com/bitnami
 helm install coder-db bitnami/postgresql \
+    --set image.repository=bitnamilegacy/postgresql
     --namespace coder \
     --set auth.username=coder \
     --set auth.password=coder \