Keep the branch gateway on the healthy uplink

Clients in VLAN 20 use 10.20.0.1 as their default gateway. DIST-2 is already healthy in HSRP group 20 with that virtual IP and priority 100. DIST-1 should normally be active, but a recent review found that it keeps forwarding as active after its routed uplink fails and does not reliably resume the role after recovery.

Repair dist-1.cfg so only HSRP group 20 provides gateway 10.20.0.1.

• DIST-1 must be active at priority 110 when healthy, yield to DIST-2 after uplink failure, and resume after recovery.
• Use Gi0/1 track object 1 with a priority decrement of 20.
• Preserve the supplied interface addressing and enabled state.