Generate TRAPI log if BTE marks API unavailable, skips subquerying it

[colleenXu]

Jackson's info from lab Slack (emphasis mine):

For context, BTE keeps track of APIs which should be considered unavailable for the duration of query execution. This occurs when a subquery to said API fails 3 times in a row with an HTTP 502 or higher, or the connection was aborted. When that happens, it logs to debug, but should also show up in the TRAPI logs as a failed subquery. From then, all subsequent subqueries to that API are skipped silently for the rest of execution.

It would be helpful if it wasn't silent! Instead, a TRAPI log could be generated saying that we're not going to subquery this API for the rest of this query's execution. (Note: is this any different in creative-mode? with parallel execution?)

FYI: I think a console log like this is already being generated.