Fix pfsense grok to support new opensense log format

[kcreddy]

What does this PR do?

Short-term fix for handling new OPNsense log format by updating the grok pattern. A permanent fix will be to switch to syslog after elastic/beats#31798 is merged

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

Related issues

• Closes [pfsense] switch from grok to syslog processor #3586

[elasticmachine]

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• Start Time: 2022-07-04T17:31:24.409+0000

• Duration: 16 min 53 sec

Test stats 🧪

Test	Results
Failed	0
Passed	45
Skipped	0
Total	45

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[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	88.889% (8/9)	👎 -7.71
Classes	88.889% (8/9)	👎 -7.71
Methods	92.063% (58/63)	👍 3.236
Lines	89.409% (650/727)	👎 -0.539
Conditionals	100.0% (0/0)	💚

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[leehinman]

LGTM