[gcp] add compute pipeline test

[gpop63]

What does this PR do?

Adds a test for the compute ingest pipeline.

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.

Author's Checklist

• [ ]

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Build stats

• Start Time: 2022-11-22T21:13:44.438+0000

• Duration: 18 min 25 sec

Test stats 🧪

Test	Results
Failed	0
Passed	53
Skipped	0
Total	53

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (6/6)	💚
Files	100.0% (6/6)	💚
Classes	100.0% (6/6)	💚
Methods	90.291% (93/103)	👎 -7.37
Lines	95.976% (1455/1516)	👎 -0.987
Conditionals	100.0% (0/0)	💚

[tommyers-elastic]

thanks for adding this gabriel. more tests ftw

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Package gcp - 2.15.1 containing this change is available at https://epr.elastic.co