Update AWS ELB ingest pipeline

[kaiyan-sheng]

What does this PR do?

This PR is to sync changes made in elastic/beats#26441 with AWS package.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• If I'm introducing a new feature, I have modified the Kibana version constraint in my package's manifest.yml file to point to the latest Elastic stack release (e.g. ^7.13.0).

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: Pull request #1212 updated

• Start Time: 2021-06-24T23:08:45.704+0000

• Duration: 19 min 47 sec

• Commit: 3740fbb

Test stats 🧪

Test	Results
Failed	0
Passed	247
Skipped	0
Total	247

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[leehinman]

LGTM