google_workspace: fix JSON error and login challenge_status handling

[efd6]

Proposed commit message

google_workspace: fix JSON error and login challenge_status handling

Also improve error reporting for cases where JSON parsing cannot be
successfully carried out. Previously JSON parsing failures would be
silently ignored leaving no indication that that was the cause of a
document not being processed correctly. With the changes here, failing
to parse the JSON results in pipeline termination with an informative
message since no furthe work can be done without the parsed JSON.

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.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Fixes [Google Workspace]: Misclassification of Successful Logins with "Challenge Passed" Status #12976

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cc @efd6

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Quality Gate failed

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5.7% Coverage on New Code (required ≥ 80%)

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