Catch acl table KeyError in caclmgrd to avoid caclmgrd not working

[ZhaohuiS]

The KeyError issue could happen during using acl-loader to delete acl rules, after KeyError, the caclmgrd still show active:running, but it doesn't respond to any action from acl-loader.
For avoiding caclmgrd got stuck, catch the KeyError exception and let program continue.

<85>Jan 28 22:39:37 SJC20-0101-0203-17T1 sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader delete IPV6_SSH_ONLY
<30>Jan 28 22:39:37 SJC20-0101-0203-17T1 caclmgrd[4612]: ACL config not stable for namespace '': 1 changes detected in the past 0.5 seconds. Skipping update ...
<30>Jan 28 22:39:37 sonic caclmgrd[4612]: ACL config not stable for namespace '': 2 changes detected in the past 0.5 seconds. Skipping update ...
<85>Jan 28 22:39:37 sonic sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader delete SNMP_ACL
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: ACL config for namespace '' has not changed for 0.5 seconds. Applying updates ...
<30>Jan 28 22:39:38 sonic caclmgrd[2020138]: Device "eth1-midplane" does not exist.
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: Translating ACL rules for control plane ACL 'IPV6_SNMP_ACL' (service: 'SNMP')
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: Translating ACL rules for control plane ACL 'SNMP_ACL' (service: 'SNMP')
<28>Jan 28 22:39:38 sonic caclmgrd[4612]: Unable to determine if ACL table 'IPV6_SSH_ONLY' contains IPv4 or IPv6 rules. Skipping table...
<28>Jan 28 22:39:38 sonic caclmgrd[4612]: Unable to determine if ACL table 'IPV6_SNMP_ACL' contains IPv4 or IPv6 rules. Skipping table...
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: Translating ACL rules for control plane ACL 'IPV6_SSH_ONLY' (service: 'SSH')
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: Translating ACL rules for control plane ACL 'SSH_ONLY' (service: 'SSH')
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: Traceback (most recent call last):
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:     caclmgr.run()
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:   File "/usr/local/bin/caclmgrd", line 1022, in main
<30>Jan 28 22:39:38 sonic caclmgrd[4612]: KeyError: 'SNMP_ACL'
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:   File "/usr/local/bin/caclmgrd", line 1026, in <module>
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:     main()
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:     if self.config_db_map[namespace].get_table(self.ACL_TABLE)[acl_table]["type"] == self.ACL_TABLE_TYPE_CTRLPLANE:
<30>Jan 28 22:39:38 sonic caclmgrd[4612]:   File "/usr/local/bin/caclmgrd", line 992, in run
<85>Jan 28 22:39:38 sonic sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader delete SSH_ONLY
<85>Jan 28 22:39:39 sonic sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader update full /etc/sonic/acl.json --table_name IPV6_SNMP_ACL
<12>Jan 28 22:40:02 sonic acl-loader: EVERFLOWSTATIC table does not exist
<85>Jan 28 22:40:03 sonic sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader update full /etc/sonic/acl.json --table_name SNMP_ACL
<12>Jan 28 22:40:25 sonic acl-loader: EVERFLOWSTATIC table does not exist
<85>Jan 28 22:40:27 sonic sudo: sonic_user : TTY=pts/0 ; PWD=/home/sonic_user ; USER=root ; COMMAND=/usr/local/bin/acl-loader update full /etc/sonic/acl.json --table_name IPV6_SSH_ONLY

[ZhaohuiS]

The issue was fixed in #62