[Filebeat] Update checkpoint.source_object mapping

[legoguy1000]

What does this PR do?

Changes checkpoint.source_object from Long to Keyword per https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk144192

Why is it important?

Field should be a string, not number

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Author's Checklist

• [ ]

How to test this PR locally

cd x-pack/filebeat
TESTING_FILEBEAT_MODULES=checkpoint mage -v pythonIntegTest

Related issues

• Closes [Check Point] Field checkpoint.source_object mapped incorrectly as long #25124

Use cases

Screenshots

Logs

[elasticmachine]

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• Build Cause: andrewkroh commented: run tests

• Start Time: 2021-04-26T14:49:22.492+0000

• Duration: 106 min 32 sec

• Commit: 494f58d

Test stats 🧪

Test	Results
Failed	0
Passed	13707
Skipped	2285
Total	15992

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Test stats 🧪

Test	Results
Failed	0
Passed	13707
Skipped	2285
Total	15992

[legoguy1000]

@andrewkroh @andrewstucki could you run the CI tests?

[andrewkroh]

run tests

[elasticmachine]

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

[legoguy1000]

@andrewkroh I think we're good to merge unless you have any comments.

[andrewkroh]

run tests

[legoguy1000]

Looks like all the tests passed

[andrewkroh]

I suspected that this fail after it merged to master because in master I pinned the geoip database version which affected the contents of the generated files. So I updated the branch and regenerated the test output files.

[andrewkroh]

run tests