feat: Warn on shutdown if trainer is connected #8136

Job	Run time
Run tests (x9dp2019)	3m 8s
Run tests (tx16s)	6m 51s
Run tests (nv14)	6m 42s
Run tests (el18)	8m 12s
Run tests (t12)	4m 3s
Run tests (t16)	6m 54s
Run tests (t18)	6m 52s
Run tests (t8)	2m 58s
Run tests (tlite)	3m 42s
Run tests (t20)	3m 49s
Run tests (tx12)	3m 13s
Run tests (x10)	6m 50s
Run tests (x12s)	7m 14s
Run tests (x7)	3m 2s
Run tests (x9d)	4m 11s
Run tests (x9dp)	3m 31s
Run tests (x9e)	3m 51s
Run tests (x9lite)	3m 37s
Run tests (x9lites)	3m 17s
Run tests (xlite)	3m 17s
Run tests (xlites)	4m 25s
Run builds (nv14;el18)	7m 14s
Run builds (t12)	2m 30s
Run builds (t16)	4m 58s
Run builds (t18)	4m 17s
Run builds (t8;zorro;pocket;commando8)	5m 3s
Run builds (tlite;tpro;tprov2;lr3pro)	6m 4s
Run builds (t20)	2m 32s
Run builds (tx12;tx12mk2;boxer)	4m 3s
Run builds (tx16s)	5m 0s
Run builds (x10;x10-access)	9m 10s
Run builds (x12s)	5m 30s
Run builds (x7;x7-access)	3m 5s
Run builds (x9d;x9dp;x9dp2019)	4m 6s
Run builds (x9e;x9e-hall)	2m 59s
Run builds (x9lite;x9lites)	3m 35s
Run builds (xlite;xlites)	4m 8s
	2h 53m 53s

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