HUE-5959 [backend] Allow 0 as a setting for conn_max_age
HUE-5959 [backend] Allow 0 as a setting for conn_max_age

The default config value of 0 caused an exception.

todaychi/hue,cloudera/hue,todaychi/hue,cloudera/hue,kawamon/hue,cloudera/hue,xq262144/hue,cloudera/hue,jayceyxc/hue,jayceyxc/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,jayceyxc/hue,cloudera/hue,todaychi/hue,jayceyxc/hue,todaychi/hue,todaychi/hue,cloudera/hue,cloudera/hue,kawamon/hue,xq262144/hue,xq262144/hue,xq262144/hue,xq262144/hue,cloudera/hue,cloudera/hue,jayceyxc/hue,jayceyxc/hue,xq262144/hue,kawamon/hue,todaychi/hue,cloudera/hue,kawamon/hue,jayceyxc/hue,cloudera/hue,cloudera/hue,kawamon/hue,kawamon/hue,cloudera/hue,todaychi/hue,kawamon/hue,kawamon/hue,todaychi/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,xq262144/hue,xq262144/hue,cloudera/hue,kawamon/hue,kawamon/hue,kawamon/hue,xq262144/hue,kawamon/hue,kawamon/hue,cloudera/hue,jayceyxc/hue,jayceyxc/hue,todaychi/hue