[Frontend] Avoid surfacing errors in the UI that are caused by failures in interacting with Cost Explorer, regardless the failure root cause.

[gmarciani]

Avoid surfacing errors in the UI that are caused by failures in interacting with Cost Explorer, regardless the failure root cause.

Changes

1. Replaced the error notification at the UI level with a console log
2. Added unit tests to cover the scenario

How Has This Been Tested?

1. Unit tests
2. Manual test verifying that errors are not displayed in the UI when access to Cost Explorer is forbidden by a permissions boundary
3. Manual test verifying that the cost monitoring feature behaves as expected in the UI when the permission boundary is removed and the access to Cost Explorer has recovered.

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