fix(Zendesk) - improve error handling

[aubin-tchoi]

Description

• Some 404 errors were hidden and not correctly bubbled up in fetchFromZendeskWithRetries, which should never be the place where we handle any kind of error whatsoever.
• This PR proposes to let fetchFromZendeskWithRetries only rethrow errors, and from then handle accordingly in each function. For instance we can design a function that checks whether an article exist by fetching and catching 404 only.
• From then we will be able to investigate https://app.datadoghq.eu/logs?query=%28%22Activity%20failed%22%20OR%20%22Unhandled%20activity%20error%22%29%20%40attempt%3A%3E19%20%40dd.service%3Aconnectors-worker&agg_m=count&agg_m_source=base&agg_t=count&cols=host%2Cservice&event=AwAAAZPke_Y-HVya5wAAABhBWlBrZV94LUFBRDBRU0lqdzNaTklBQUIAAAAkMDE5M2U0N2UtYWIxYi00NzY5LWE1M2QtM2VjYjhjZTM5MjFkAAAYHA&fromUser=true&graphType=flamegraph&messageDisplay=inline&refresh_mode=sliding&sort=time&spanID=6000198897476506285&storage=hot&stream_sort=time%2Cdesc&viz=stream&from_ts=1734704698707&to_ts=1734705598707&live=true

Risk

• Low

Deploy Plan

• Deploy connectors.