[MONGODB]: Add initial alert rule templates

[shmsr]

Proposed commit message

This PR introduces the first set of alert rule templates for the MongoDB integration.

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

Related issues

• Closes https://github.com/elastic/obs-integration-team/issues/633

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: e03d1e0

Failed CI Steps

• Check integrations mongodb

History

cc @shmsr