[monit] Fix status error due to shebang change

[lolyu]

lldpmgrd, bgpcfgd, and bgpmon are reported error status not running due
to recent change of shebang to use Python3. Modifying the argument of
process_checker to follow this change.

fixes #5864

Signed-off-by: Longxiang Lyu lolv@microsoft.com

- Why I did it

Nov  9 04:36:38.750321 str-dx010-acs-4 ERR monit[519]: 'lldp|lldpmgrd' status failed (1) -- 'python /usr/bin/lldpmgrd' is not running.
Nov  9 04:36:38.916896 str-dx010-acs-4 ERR monit[519]: 'bgp|bgpcfgd' status failed (1) -- '/usr/bin/python /usr/local/bin/bgpcfgd' is not running.
Nov  9 04:36:38.941334 str-dx010-acs-4 ERR monit[519]: 'bgp|bgpmon' status failed (1) -- '/usr/bin/python /usr/local/bin/bgpmon' is not running.

• actually command line for lldpmgrd, bgpcfgd and bgpmon:

admin@str-dx010-acs-4:~$ ps aux | grep python3
root       430  0.0  0.5  33184 21784 pts/0    S    03:41   0:00 python3 /usr/bin/lldpmgrd
root      1181  0.0  0.5 110828 21872 ?        Ss   Nov08   0:05 /usr/bin/python3 /usr/local/bin/caclmgrd
root      1182  0.5  0.4  27512 16844 ?        Ss   Nov08   3:03 /usr/bin/python3 /usr/local/bin/procdockerstatsd
root      2192  5.9  0.8 121280 35508 pts/0    Sl   03:41   6:06 python3 -m sonic_ax_impl
admin    21134  0.0  0.0   6824   892 pts/0    S+   05:25   0:00 grep python3
root     29809  0.0  0.6 258356 25504 ?        Ssl  03:40   0:01 python3 /usr/bin/core_uploader.py
root     31445  0.0  0.6 256580 27808 ?        Sl   03:41   0:00 python3 /usr/bin/docker-wait-any -s swss -d syncd teamd
root     32074  0.0  0.5  39704 23836 pts/0    S    03:41   0:01 /usr/bin/python3 /usr/local/bin/bgpcfgd
root     32092  0.0  0.3  21980 15180 pts/0    S    03:41   0:00 /usr/bin/python3 /usr/local/bin/bgpmon

- How I did it

- How to verify it

- Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)