Fix CloudwatchClient error when run with a nil timezone

[zachmargolis]

when we run the ./bin/query-cloudwatch script, we're running outside of Rails, so Time.zone is nil, so we get errors like this. Switching to Time.at lets us work around this

Example:

identity-idp/lib/reporting/cloudwatch_client.rb:169:in `rescue in fetch_one': undefined method `at' for nil:NilClass (NoMethodError)

        log(:warn, "query end_time=#{end_time} (#{Time.zone.at(end_time)}) is before Cloudwatch Insights availability, skipping")
                                                           ^^^
  from identity-idp/lib/reporting/cloudwatch_client.rb:155:in `fetch_one'
  from identity-idp/lib/reporting/cloudwatch_client.rb:88:in `block (2 levels) in fetch'
.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/aws-sdk-core-3.179.0/lib/seahorse/client/plugins/raise_response_errors.rb:17:in `call': End time should not be before the service was generally available (Service: AWSLogs; Status Code: 400; Error Code: InvalidParameterException; Request ID: c53d3718-df37-436c-a510-02675dd2141c; Proxy: null) (Aws::CloudWatchLogs::Errors::InvalidParameterException)

[ThatSpaceGuy]

Looks good!

[n1zyy]

Thanks, Rubocop, for complaining that we're not reintroducing the bug. 😆

[n1zyy]

Does this imply zonebie is calling Time.zone itself? No issue with it review-wise, just curious.

[zachmargolis]

I tried setting Time.zone = nil in a before filter, in the spec itself, etc, and they all got overridden, so I had to stub to get the spec to actually run with a nil timezone