Update test_macsec.py (sonic-net#3549)

What I did
Provide an explicit value for send_sci in the macsec vstest

Why I did it

The kernel 5.15 requires the send_sci to be true if the sci value was provided explicitly.

tests/test_macsec.py

@@ -424,6 +424,7 @@ def init_macsec(
         wpa.init_macsec_port(port_name)
         wpa.config_macsec_port(port_name, {"enable_protect": True})
         wpa.config_macsec_port(port_name, {"enable_encrypt": True})
+        wpa.config_macsec_port(port_name, {"send_sci": True})
         wpa.config_macsec_port(
             port_name,
             {