Remove fallbacks to old flow for cloud access

[AlexVulaj]

What type of PR is this?

cleanup

What this PR does / Why we need it?

Currently the bp-cli falls back to the old flow if it fails to assume cloud credentials/console access with the new flow. This was a good fallback initially, but at this point it masks legitimate errors and prevents SREs from knowing what's wrong. This PR removes that fallback in place of passing along logs.

Which Jira/Github issue(s) does this PR fix?

OSD-21438

Pre-checks (if applicable)

• Ran unit tests locally
• Validated the changes in a cluster
• Included documentation changes with PR

I tested these changes against non-STS clusters, as well as STS clusters using both the old and new flow.

[openshift-ci]

@AlexVulaj: all tests passed!

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[geowa4]

/lgtm

[xiaoyu74]

• Built a bp-cli binary based on this PR to run towards a previous cluster osd-v4prod-aws (old flow access method) we used to test and the old flow related functions can handle the access properly.

• Updated if-else block for the 2nd conditions in IsolatedBackplaneAccess looks clear:

	return supportRoleArn.Resource != OldFlowSupportRole, nil
	} else {
		return false, nil
	}

[xiaoyu74]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AlexVulaj, geowa4, xiaoyu74

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