[o365] Add system tests

[marc-gr]

What does this PR do?

• Removes log input only used for system tests.
• Fixes the pipeline and config for o365audit input, which was inadvertently broken due to the lack of system tests: o365audit input does not have a raw message field to parse, but a o365audit object already parsed.
• Changes api setting type to yaml.
• Changes tenant_names description and configuration: the option is a text but was treated like an object, which was causing the tests to break. This was not showing up in tests because the option was not set in the system tests for the log input.
• Fixes pipeline tests configuration.
• Removes duplicate pipeline test configs and add a common one.
• Add system tests for o365audit

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.
• If I'm introducing a new feature, I have modified the Kibana version constraint in my package's manifest.yml file to point to the latest Elastic stack release (e.g. ^7.13.0).

Related issues

• Relates Move Security integrations to GA #961
• Depends on [filebeat] Add preserve_original_event option to o365audit input beats#26273

[elasticmachine]

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Build stats

• Build Cause: Pull request #1119 updated

• Start Time: 2021-06-15T10:19:21.244+0000

• Duration: 11 min 27 sec

• Commit: 31f136c

Test stats 🧪

Test	Results
Failed	0
Passed	25
Skipped	0
Total	25

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[elasticmachine]

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

[P1llus]

LGTM, just added a quick comment