Optionally use secret to set env variables in setup credentials job

[LilMonk]

Give an option to use a kubernetes secret for setting these env variables.

charts/stable/yugabyte/templates/hooks/setup-credentials-job.yaml

Lines 32 to 51 in 8c8acc0

	{{- if .Values.authCredentials.ysql.user }}
	- name: YSQL_USER
	value: "{{ .Values.authCredentials.ysql.user }}"
	{{- end }}
	{{- if .Values.authCredentials.ysql.password }}
	- name: YSQL_PASSWORD
	value: "{{ .Values.authCredentials.ysql.password }}"
	{{- end }}
	{{- if .Values.authCredentials.ysql.database }}
	- name: YSQL_DB
	value: "{{ .Values.authCredentials.ysql.database }}"
	{{- end }}
	{{- if .Values.authCredentials.ycql.user }}
	- name: YCQL_USER
	value: "{{ .Values.authCredentials.ycql.user }}"
	{{- end }}
	{{- if .Values.authCredentials.ycql.password }}
	- name: YCQL_PASSWORD
	value: "{{ .Values.authCredentials.ycql.password }}"
	{{- end }}