backups: split config and policy

keeping them together makes the test/validation quite complicated.
for example, when policy is changed, we test the storage backends

part of #817

src/cron.js

@@ -161,7 +161,7 @@ async function startJobs() {
     const allSettings = await settings.list();
 
     const tz = allSettings[settings.TIME_ZONE_KEY];
-    backupConfigChanged(allSettings[settings.BACKUP_CONFIG_KEY], tz);
+    backupPolicyChanged(allSettings[settings.BACKUP_POLICY_KEY], tz);
     autoupdatePatternChanged(allSettings[settings.AUTOUPDATE_PATTERN_KEY], tz);
     dynamicDnsChanged(allSettings[settings.DYNAMIC_DNS_KEY]);
 }
@@ -185,16 +185,16 @@ async function handleSettingsChanged(key, value) {
     }
 }
 
-function backupConfigChanged(value, tz) {
+function backupPolicyChanged(value, tz) {
     assert.strictEqual(typeof value, 'object');
     assert.strictEqual(typeof tz, 'string');
 
-    debug(`backupConfigChanged: schedule ${value.schedulePattern} (${tz})`);
+    debug(`backupPolicyChanged: schedule ${value.schedule} (${tz})`);
 
     if (gJobs.backup) gJobs.backup.stop();
 
     gJobs.backup = new CronJob({
-        cronTime: value.schedulePattern,
+        cronTime: value.schedule,
         onTick: async () => await safe(backups.startBackupTask(AuditSource.CRON), { debug }),
         start: true,
         timeZone: tz