Make client `updates download` get signed builds if possible #4333

Job	Run time
Pre-commit checks	3m 12s
Integration Tests (f40)	8m 29s
Build Documentation (f40)	1m 33s
Integration Tests (f41)	8m 30s
Build Documentation (f41)	2m 16s
Integration Tests (rawhide)	10m 40s
Build Documentation (pip)	3m 0s
Build the RPMS (f40)	1m 27s
Build Documentation (rawhide)	1m 11s
Build the RPMS (f41)	1m 22s
Unit Tests (f40, bodhi-client)	1m 14s
Build the RPMS (rawhide)	1m 18s
Unit Tests (f40, bodhi-messages)	1m 7s
Unit Tests (f40, bodhi-server)	4m 15s
Unit Tests (f41, bodhi-client)	1m 5s
Unit Tests (f41, bodhi-messages)	1m 4s
Unit Tests (f41, bodhi-server)	3m 19s
Unit Tests (pip, bodhi-client)	2m 48s
Unit Tests (pip, bodhi-messages)	2m 49s
Unit Tests (pip, bodhi-server)	5m 20s
Unit Tests (rawhide, bodhi-client)	1m 18s
Unit Tests (rawhide, bodhi-messages)	1m 7s
Unit Tests (rawhide, bodhi-server)	3m 57s
Diff-cover check	14s
	1h 12m 35s

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