[docker-iccpd] limit privileged flag for iccpd container (#17835)

### Why I did it
HLD implementation: Container Hardening (https://github.com/sonic-net/SONiC/pull/1364)
##### Work item tracking
- Microsoft ADO **(number only)**: 14807420
#### How I did it
Reduce linux capabilities in privileged flag

#### How to verify it
Check container's settings: Privileged is false and container only has default Linux caps, does not have extended caps.
```
admin@vlab-01:~$ docker inspect iccpd | grep Privi
            "Privileged": false,


admin@vlab-01:~$ docker exec -it iccpd bash
root@vlab-01:/# capsh --print
Current: cap_chown,cap_dac_override,cap_fowner,cap_fsetid,cap_kill,cap_setgid,cap_setuid,cap_setpcap,cap_net_bind_service,cap_net_raw,cap_sys_chroot,cap_mknod,cap_audit_write,cap_setfcap=ep
```

rules/docker-iccpd.mk

@@ -21,7 +21,7 @@ SONIC_INSTALL_DOCKER_DBG_IMAGES += $(DOCKER_ICCPD_DBG)
 endif
 
 $(DOCKER_ICCPD)_CONTAINER_NAME = iccpd
-$(DOCKER_ICCPD)_RUN_OPT += --privileged -t
+$(DOCKER_ICCPD)_RUN_OPT += -t
 $(DOCKER_ICCPD)_RUN_OPT += -v /etc/sonic:/etc/sonic:ro
 $(DOCKER_ICCPD)_RUN_OPT += -v /etc/timezone:/etc/timezone:ro