Modify fare_transfer_rule_with_forbidden_transfer_count so leg_group_id fields can be empty

[emmambd]

Describe the problem

Currently, FareTransferRuleWithForbiddenTransferCountNotice triggers when both from_leg_group_id and to_leg_group_id are empty and transfer_count exists.

According to the spec, it should be ok to have transfer_count when from_leg_group_id and to_leg_group_id are empty.

Proposed solution

Modify fare_transfer_rule_with_forbidden_transfer_count so from_leg_group_id and to_leg_group_id can be empty when transfer count exists.

Alternatives you've considered

No response

Additional context

No response