Cherry-pick #21732 to 7.x: [Filebeat] Add check for context.DeadlineExceeded error

[kaiyan-sheng]

Cherry-pick of PR #21732 to 7.x branch. Original message:

What does this PR do?

This PR adds a check for context.DeadlineExceeded error and reports an INFO level log message instead.

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.

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Pinging @elastic/integrations-platforms (Team:Platforms)

[elasticmachine]

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Build stats

• Build Cause: [Pull request #21771 opened]

• Start Time: 2020-10-13T19:30:20.980+0000

• Duration: 77 min 35 sec

Test stats 🧪

Test	Results
Failed	0
Passed	1947
Skipped	259
Total	2206