[7.x](backport #28509) Add latency config option for aws-cloudwatch input

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This is an automatic backport of pull request #28509 done by Mergify.

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• Start Time: 2021-10-19T13:44:52.499+0000

• Duration: 108 min 27 sec

• Commit: 468137a

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Test	Results
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Passed	8328
Skipped	1201
Total	9529

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