Drop redundant call report and task report tests

[Ichimonji10]

As of c6308d4,

pulp_smash.api.safe_handler and pulp_smash.api.json_handler
check for errors in task reports and call reports, and raise
TaskReportError or CallReportError respectively if one is found.

As a result, many test methods are no longer necessary. Let's walk through tests that explicitly check call reports and task reports, drop redundant checks, and drop the code that bothers to collect and save those call reports and task reports if possible.

[Ichimonji10]

#121 makes use of this new behaviour to great effect.

[elyezer]

Had an IRC chat session with @Ichimonji10 and have clarified the following:

Both api.safe_handler and api.json_handler call _handle_202, which calls _check_call_report and _check_tasks. _check_tasks() ensures that each task's "error", "exception" and "traceback" fields. Given that, there's no reason to also check those fields in unit tests.

[Ichimonji10]

Thanks for clarifying.