* Change unit of duration params to hours to align it with duration config at other places in Loki
other configurations like periodic table duration, retention are set in hours so this change makes
duration config for backup tool consistent and easy to manage configurations
* update parent docker image for bigtable backup tool
ensure_backups_parser.add_argument('--duration',help="Duration in previous consecutive days for which backups should exist. "
"Must not be set with --period-from and --period-to",type=valid_int)
ensure_backups_parser.add_argument('--duration',help="Duration in hours for which backups should exist. "
"Must not be set with --period-from and --period-to",type=valid_duration)
ensure_backups_parser.add_argument('--period-from',type=valid_date,help="Backups should exist starting from the date. Must not be set with --duration")