Ignore context cancelled in operator

[michalpristas]

What does this PR do?

This PR guards HandleConfig func with filter resulting in ignoring context.Canceled errors.
Ignoring does not have any functional impact but it avoids spamming logs with false failures.

Why is it important?

Fixes: #27057

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.

[elasticmachine]

Pinging @elastic/agent (Team:Agent)

[elasticmachine]

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• Start Time: 2021-08-03T07:55:52.290+0000

• Duration: 72 min 25 sec

• Commit: 18ace25

Test stats 🧪

Test	Results
Failed	0
Passed	7012
Skipped	16
Total	7028

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Test stats 🧪

Test	Results
Failed	0
Passed	7012
Skipped	16
Total	7028

[blakerouse]

Looks good.

Like the use of the defer to perform the filter.

[amolnater-qasource]

Hi @EricDavisX
We are validating this PR in lieu of reported issue at #27057
We have revalidated this on 7.15.0 BC-2 and found it fixed now.

Observations:

• No Failed to render configuration error logs observed when windows agent is installed with only System integration.

Build details:

Build: 43832
Commit: b7ad04c31d99f54fba754f1ad59dc8012e0fd4d1
Artifact Link: https://staging.elastic.co/7.15.0-642a73fa/downloads/beats/elastic-agent/elastic-agent-7.15.0-windows-x86_64.zip

Screenshot:

Thanks