checkpoint: Fix parsing error due to trailing spaces

[adriansr]

What does this PR do?

Messages from the checkpoint firewall can contain trailing spaces at the end. This patch makes the parsing less strict to allow for trailers.

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.

[elasticmachine]

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

[elasticmachine]

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Build stats

• Start Time: 2022-04-07T17:47:26.850+0000

• Duration: 15 min 21 sec

Test stats 🧪

Test	Results
Failed	0
Passed	9
Skipped	0
Total	9

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