Please try this config:
set firewall family inet filter VPN-cos term T1 from source-address 10.100.11.0/24 <-----------Site-A LAN Address
set firewall family inet filter VPN-cos term T1 from destination-address 10.100.22.0/24 <------- Site-B LAN address
set firewall family inet filter VPN-cos term T1 then forwarding-class assured-forwarding
set firewall family inet filter VPN-cos term T1 then accept
set firewall family inet filter VPN-cos term T1 then count VPN-Traffic
set firewall family inet filter VPN-cos term default then accept
set interfaces ge-0/0/0 unit 0 family inet filter input VPN-cos <------ Site-A Lan facing interface
set class-of-service schedulers af-vpn transmit-rate percent 25
set class-of-service schedulers af-vpn buffer-size percent 25
set class-of-service schedulers af-vpn priority medium-high
set class-of-service scheduler-maps af-vpn-map forwarding-class assured-forwarding scheduler af-vpn
set interfaces ge-0/0/1 per-unit-scheduler
set class-of-service interfaces ge-0/0/1 unit 0 scheduler-map af-vpn-map <------- ISP facing interface
show firewall <-- Verify the hitcount
show interface ge-0/0/1 extensive | find "Queue counters:" <------- verify counters in Assured forwarding queue