Change to use one period between start and end time

[kaiyan-sheng]

What does this PR do?

This PR is to change startTime and endTime of GetMetricData API in cloudwatch metricbeat to be only one collection period apart. Bug in previous code is:

• First Metricbeat collection cycle: startTime = 06:50:35 endTime = 07:00:35 -> cloudwatch metric timestamp = 06:55:00

• Second Metricbeat collection cycle: startTime = 06:55:35 endTime = 07:05:35 -> cloudwatch metric timestamp = 06:55:00

The problem is caused by the startTime and endTime parameters in AWS CloudWatch GetMetricData API only look at the hour and minute (e.g: 06:50 and 07:00) in a timestamp. And also the gap between startTime and endTime is double the period, which causes more than one data point gets returned.

This PR is to first round the timestamps to ignore seconds. Then change startTime to be one collection period ahead of endTime. If no data is collected, which means services have a delay to send metrics into AWS CloudWatch. In this case, latency config parameter should be used.

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.

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b start_end_time upstream/start_end_time
git merge upstream/master
git push upstream start_end_time

[elasticmachine]

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• Start Time: 2021-08-16T15:37:19.814+0000

• Duration: 106 min 44 sec

• Commit: 0b3074b

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Total	11952

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Passed	9435
Skipped	2517
Total	11952