Support migration of log indexes without Flex tier

[k4ji]

Replaces #328 to resolve CI issues related to forked PRs.
Closes #332

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What does this PR do?

The Log Indexes API currently returns num_flex_logs_retention_days as 0 instead of null for indexes without the Flex tier, leading to migration failures when attempting to create or update log indexes in an organization where Flex logs are not enabled.

This PR ensures that when num_flex_logs_retention_days is 0, the field is removed from the imported resource, preventing unnecessary Flex log-related parameters from being included in migration requests.

Description of the Change

• Added a check in the import method to remove num_flex_logs_retention_days when its value is 0.

Alternate Designs

An alternative approach considered was to add a check in both the create_resource and update_resource methods to remove num_flex_logs_retention_days when its value is 0.

However, this was discarded because the issue originates from the Log Indexes API's get all indexes response, which returns num_flex_logs_retention_days as 0 instead of null. The create and update APIs do not have this issue, so modifying those methods would introduce unnecessary logic for a problem that only occurs in the retrieval step.

Verification Process

Since an existing test for log index migration behavior is currently skipped, no new tests were added or modified.
Instead, manual verification was performed using the import command:

1. Ran import targeting log indexes with and without the Flex tier.
2. Verified that the resulting JSON output does not include num_flex_logs_retention_days for indexes without the Flex tier.

...
  "with-flex-log": {
    "name": "with-flex-log",
    ...
    "num_flex_logs_retention_days": 180
  },
  "without-flex-log": {
    "name": "without-flex-log"
    ...
    // No num_flex_logs_retention_days entry
  }
}

Additional Notes

Release Notes

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[michael-richey]

Thanks for the fix!