Only use crumbIssuer if needed

[sboardwell]

This PR removes unneccessary requests to the /crumbIssuer endpoint when using an API token.

• the decision of whether a crumb is needed is made at agent creation time
• subsequent calls to sync labels, etc, request the crumb only if needed

Testing done

• Tested both manually and through adding a test case

Submitter checklist

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• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
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