When paying through a direct channel, direct_pay_override() creates a
route bypassing the normal routing path, which skips the CLTV budget
check in payment_getroute(). This allows payments to succeed even when
maxdelay is set below the required min_final_cltv_expiry.
Add a check in direct_pay_override() to verify the required CLTV
doesn't exceed cltv_budget before using the direct channel shortcut.
If it exceeds, skip the direct channel and let normal routing handle
the failure with a proper error message.
Fixes: #8609
Changelog-Fixed: pay: `maxdelay` parameter now enforced for direct channel payments
bc3b9b4f11