Fix timestamp parser error in cisco_catalyst plugin

[ericwholt]

In customer environment we were seeing a * in front of the timestamp which would cause the regex to fail to parse. Updated regex and routers to handle this without error.

[jsirianni]

Couple things

1. Can you provide original logs that should work from the master branch? I have examples that this PR is intended to fix
2. The logs I am working with are not parsing, for example:

input:

[12:51 PM] 54: *Feb 28 19:02:23 EST: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test

output:

{
  "timestamp": "2021-10-18T10:54:14.155642-04:00",
  "severity": 0,
  "labels": {
    "log_type": "cisco_catalyst",
    "net.host.ip": "::",
    "net.host.port": "5555",
    "net.peer.ip": "::1",
    "net.peer.port": "56873",
    "net.transport": "IP.UDP",
    "plugin_id": "cisco_catalyst"
  },
  "record": {
    "message": "[12:51 PM] 54: *Feb 28 19:02:23 EST: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test"
  }
}

I am using the latest stanza and this branch of plugins. With this config

pipeline:
- type: cisco_catalyst
  listen_port: 5555
- type: stdout

this command

echo '[12:51 PM] 54: *Feb 28 19:02:23 EST: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test' | nc -u localhost 5555

[ericwholt]

I used this log entry to test.

54: *Feb 28 19:02:23 EST: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test

It outputs

{
  "timestamp": "2021-02-28T19:02:23-05:00",
  "severity": 30,
  "severity_text": "6",
  "labels": {
    "log_type": "cisco_catalyst",
    "net.host.ip": "::",
    "net.host.port": "514",
    "net.peer.ip": "127.0.0.1",
    "net.peer.port": "59094",
    "net.transport": "IP.UDP",
    "plugin_id": "cisco_catalyst"
  },
  "record": {
    "facility_text": "DHCP",
    "message": "Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test",
    "mnemonic": "ADDRESS_ASSIGN",
    "sequence_number": "54"
  }
}

This command

nc -w1 -u localhost 514 <<< '54: *Feb 28 19:02:23 EST: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan1 assigned DHCP address 10.0.0.150, mask 255.255.0.0, hostname test'