[7.x](backport #27126) Add support for web identity provider in aws

[mergify]

This is an automatic backport of pull request #27126 done by Mergify.

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Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

💚 Build Succeeded

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• Start Time: 2021-08-12T08:18:29.320+0000

• Duration: 212 min 10 sec

• Commit: e676e7c

Test stats 🧪

Test	Results
Failed	0
Passed	52244
Skipped	5246
Total	57490

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Test stats 🧪

Test	Results
Failed	0
Passed	52244
Skipped	5246
Total	57490

[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 mergify/bp/7.x/pr-27126 upstream/mergify/bp/7.x/pr-27126
git merge upstream/7.x
git push upstream mergify/bp/7.x/pr-27126