Fix broken auto-generated Rego rule (#769)

Default Rego policy generated from the rules in some cases is broken.
This change fixes the Rego template for rules to generate policies.

Also, file store load constantly regenerates policy objects from rules.
It allows updating/fixing of the default Rego template during releases.

management/server/file_store.go

@@ -121,15 +121,25 @@ func restore(file string) (*FileStore, error) {
 			store.PrivateDomain2AccountID[account.Domain] = accountID
 		}
 
-		// if no policies are defined, that means we need to migrate Rules to policies
-		if len(account.Policies) == 0 {
+		// TODO: policy query generated from the Go template and rule object.
+		//       We need to refactor this part to avoid using templating for policies queries building
+		//       and drop this migration part.
+		policies := make(map[string]int, len(account.Policies))
+		for i, policy := range account.Policies {
+			policies[policy.ID] = i
+		}
+		if account.Policies == nil {
 			account.Policies = make([]*Policy, 0)
-			for _, rule := range account.Rules {
-				policy, err := RuleToPolicy(rule)
-				if err != nil {
-					log.Errorf("unable to migrate rule to policy: %v", err)
-					continue
-				}
+		}
+		for _, rule := range account.Rules {
+			policy, err := RuleToPolicy(rule)
+			if err != nil {
+				log.Errorf("unable to migrate rule to policy: %v", err)
+				continue
+			}
+			if i, ok := policies[policy.ID]; ok {
+				account.Policies[i] = policy
+			} else {
 				account.Policies = append(account.Policies, policy)
 			}
 		}