superuser, superuserPassword and secretKey forced to specify insecurely in values.yaml

[srinathh]

in backend-statefulset.yaml, parameters from value.yaml are directly copied into value. This prevents Kubernetes Secrets from being used & instead requires hard-coding these into values.yaml. With this implementaion, if we use Kubernetes Secrets in values.yaml, a string representation of the yaml gets copied over instead of the correct reference.

            - name: LANGFLOW_SUPERUSER
              value: "{{ .Values.langflow.backend.superuser | default "admin" }}"
            - name: LANGFLOW_SUPERUSER_PASSWORD
              value: "{{ .Values.langflow.backend.superuserPassword | default (randAlphaNum 32) }}"
            - name: LANGFLOW_SECRET_KEY
              value: "{{ .Values.langflow.backend.secretKey | default (randAlphaNum 32) }}"

Database secrets are correctly handled and implementing this style will let secrets be used for superuser as well

            - name: LF_CHART_EXTERNALDB_DATABASE
            {{- toYaml .Values.langflow.backend.externalDatabase.database | nindent 14 }}
            - name: LF_CHART_EXTERNALDB_USER
            {{- toYaml .Values.langflow.backend.externalDatabase.user | nindent 14 }}
            - name: LF_CHART_EXTERNALDB_PASSWORD
            {{- toYaml .Values.langflow.backend.externalDatabase.password | nindent 14 }}

Additionally, setting admin password as a random default is worse than useless as then no one can ever login. It should not be optional. Similarly, SecretKey is ideally not optional if autologin is provided