Backport of api: trim space of error response output into release/1.3.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #14145 to be assessed for backporting due to the inclusion of the label backport/1.3.x.

The below text is copied from the body of the original PR.

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This PR does a strings.TrimSpace on the response body of a failed API request, so that an error response is not extended with unwanted whitespace.

before:

➜ nomad job run bad.nomad
Error submitting job: Unexpected response code: 500 (1 error occurred:
	* Task group cache validation failed: 1 error occurred:
	* Task group service validation failed: 1 error occurred:
	* Services are not unique: [group->foo]





)

after:

➜ nomad job run bad.nomad
Error submitting job: Unexpected response code: 500 (1 error occurred:
	* Task group cache validation failed: 1 error occurred:
	* Task group service validation failed: 1 error occurred:
	* Services are not unique: [group->foo])

[github-actions]

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