[management] Add option to disable default all-to-all policy (#3970)

This PR introduces a new configuration option `DisableDefaultPolicy` that prevents the creation of the default all-to-all policy when new accounts are created. This is useful for automation scenarios where explicit policies are preferred.
### Key Changes:
- Added DisableDefaultPolicy flag to the management server config
- Modified account creation logic to respect this flag
- Updated all test cases to explicitly pass the flag (defaulting to false to maintain backward compatibility)
- Propagated the flag through the account manager initialization chain

### Testing:

- Verified default behavior remains unchanged when flag is false
- Confirmed no default policy is created when flag is true
- All existing tests pass with the new parameter

management/server/store/store.go

@@ -391,7 +391,7 @@ func addAllGroupToAccount(ctx context.Context, store Store) error {
 
 		_, err := account.GetGroupAll()
 		if err != nil {
-			if err := account.AddAllGroup(); err != nil {
+			if err := account.AddAllGroup(false); err != nil {
 				return err
 			}
 			shouldSave = true