[Helm Chart] Redis and Fernet Secret using pre-install hooks instead of lookup functions

### Apache Airflow version main (development) ### If "Other Airflow 2 version" selected, which one? _No response_ ### What happened? Problem: I was trying to use airflow as a child chart and noticed I couldn't upgrade my existing chart because the fernet secret would not get created. templates/configmaps/extra-configmaps.yaml: {{- $_ := set $annotations "helm.sh/hook" "pre-install,pre-upgrade" }} templates/secrets/extra-secrets.yaml: {{- $_ := set $annotations "helm.sh/hook" "pre-install,pre-upgrade" }} templates/secrets/fernetkey-secret.yaml: "helm.sh/hook": "pre-install" templates/secrets/redis-secrets.yaml:# relying on the "pre-install" hack to prevent changing randomly generated passwords, templates/secrets/redis-secrets.yaml: "helm.sh/hook": "pre-install" templates/secrets/redis-secrets.yaml: "helm.sh/hook": "pre-install" There are a couple references to secrets, fernet and redis secret that are using the pre-install hook to avoid them changing during helm upgrade I think this could be done with a lookup function instead ``` apiVersion: v1 kind: Secret metadata: name: my-secret labels: type: Opaque data: {{- $previousSecret := lookup "v1" "Secret" .Release.Namespace "my-secret" }} {{- if $previousSecret }} "mysecret": {{ $previousSecret.data.mysecret }} {{- else if .Values.mySecret }} "mysecret": {{ .Values.mySecret | b64enc | quote }} {{- else }} "mysecret": {{ randAlphaNum 32 | b64enc | quote }} {{- end }} ``` Because it seems that this pre-install hook was done more as a workaround than anything. ### What you think should happen instead? I think fernet secret should get created on helm upgrade if it does not exist. ### How to reproduce Try using airflow as a child chart that already has a deployed release. ### Operating System Fedora 40 ### Versions of Apache Airflow Providers _No response_ ### Deployment Official Apache Airflow Helm Chart ### Deployment details _No response_ ### Anything else? _No response_ ### A…