Fix default scan_frequency to 60s

[kaiyan-sheng]

Proposed commit message

This PR is to fix the scan_frequency default value to 1 minute. It was set to 10s by mistake while all documentations said the default is 1m. For example: https://www.elastic.co/docs/reference/beats/filebeat/filebeat-input-aws-cloudwatch#_scan_frequency

This PR also added some debug entries around start time and end time for API calls.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

I dont think so.

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @kaiyan-sheng? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elasticmachine]

Pinging @elastic/obs-ds-hosted-services (Team:obs-ds-hosted-services)

[Kavindu-Dodan]

Thank you for catching this 🙌