Add gnmi test to kvm suite (sonic-net#17138)

Summary: Add gnmi test to kvm test suite.

Approach
What is the motivation for this PR?
gnmi test is not included in the kvm test suite.

How did you do it?
Add the test to kvm test suite.

How did you verify/test it?
Run test on kvm machine.

tests/kvmtest.sh

@@ -173,6 +173,10 @@ test_t0() {
       generic_config_updater/test_portchannel_interface.py \
       generic_config_updater/test_syslog.py \
       generic_config_updater/test_vlan_interface.py \
+      gnmi/test_gnmi.py \
+      gnmi/test_gnmi_configdb.py \
+      gnmi/test_gnmi_appldb.py \
+      gnmi/test_gnmi_countersdb.py \
       override_config_table/test_override_config_table.py \
       process_monitoring/test_critical_process_monitoring.py \
       show_techsupport/test_techsupport_no_secret.py \
@@ -229,6 +233,9 @@ test_t2() {
     bmp/test_bmp_redis_instance.py \
     bmp/test_bmp_statedb.py \
     bmp/test_docker_restart.py \
+    gnmi/test_gnmi.py \
+    gnmi/test_gnmi_appldb.py \
+    gnmi/test_gnmi_countersdb.py \
     voq/test_voq_init.py"
 
     pushd $SONIC_MGMT_DIR/tests
@@ -253,6 +260,10 @@ test_t1_lag() {
     bmp/test_docker_restart.py \
     configlet/test_add_rack.py \
     container_checker/test_container_checker.py \
+    gnmi/test_gnmi.py \
+    gnmi/test_gnmi_configdb.py \
+    gnmi/test_gnmi_appldb.py \
+    gnmi/test_gnmi_countersdb.py \
     http/test_http_copy.py \
     ipfwd/test_mtu.py \
     lldp/test_lldp.py \
@@ -277,6 +288,9 @@ test_multi_asic_t1_lag() {
     bmp/test_bmp_redis_instance.py \
     bmp/test_bmp_statedb.py \
     bmp/test_docker_restart.py \
+    gnmi/test_gnmi.py \
+    gnmi/test_gnmi_appldb.py \
+    gnmi/test_gnmi_countersdb.py \
     snmp/test_snmp_default_route.py \
     snmp/test_snmp_loopback.py \
     snmp/test_snmp_pfc_counters.py \