Osquerybeat: Fix 7.15 extension start failure on windows

[aleksmaus]

What does this PR do?

Fixes the issue reported on windows, where our extension server client fails to connect to the osqueryd named pipe.

[elastic_agent.osquerybeat][error] Failed to run osqueryd: dialing pipe '\\.\pipe\elastic\osquery\d4501c4e-98f2-454c-8e46-e61b4f9a898d': open \\.\pipe\elastic\osquery\d4501c4e-98f2-454c-8e46-e61b4f9a898d: The system cannot find the file specified.

The issue is due to the change on July 8th, where the sequence of the osqueryd startup was changed. This changed the sequence back to:

1. start osqueryd
2. connect the osquery client to osqueryd (with retires)
3. start extensions server for our own config and logging plugins

The osquery client connection with retries before starting the extensions server guarantees that the osqueryd is running with the given named pipe.

Why is it important?

Fixes the issue with osquerybeat 7.15 on Windows.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas

[elasticmachine]

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• Start Time: 2021-09-10T16:32:52.019+0000

• Duration: 53 min 47 sec

• Commit: 3e76d59

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