Cherry-pick #26187 to 7.x: Add log_group_name_prefix config option for aws-cloudwatch input

[kaiyan-sheng]

Cherry-pick of PR #26187 to 7.x branch. Original message:

What does this PR do?

This PR is to add log_group_name_prefix config option into aws-cloudwatch input to equivalently support wildcard for log_group_name.

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.

How to test this PR locally

With filebeat input below, you should be able to see Filebeat starts aws-cloudwatch input to collect logs from all log groups that has names start with /aws/ecs.

filebeat.inputs:
- type: aws-cloudwatch
  credential_profile_name: elastic-beats
  log_group_name_prefix: /aws/ecs
  region_name: us-east-1

Related issues

• Closes [Filebeat] Adding wildcard support for log_group_name in cloudwatch input #21528

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Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

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Build stats

• Build Cause: Pull request #26527 opened

• Start Time: 2021-06-28T14:36:54.482+0000

• Duration: 112 min 57 sec

• Commit: 1a6bfe9

Test stats 🧪

Test	Results
Failed	0
Passed	7368
Skipped	1201
Total	8569

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Test stats 🧪

Test	Results
Failed	0
Passed	7368
Skipped	1201
Total	8569