feat: Warn on shutdown if trainer is connected #8153

Job	Run time
Run tests (x9dp2019)	3m 9s
Run tests (tx16s)	8m 54s
Run tests (nv14)	6m 45s
Run tests (el18)	10m 29s
Run tests (t12)	3m 6s
Run tests (t16)	7m 20s
Run tests (t18)	8m 4s
Run tests (t8)	3m 17s
Run tests (tlite)	3m 14s
Run tests (t20)	4m 12s
Run tests (tx12)	3m 22s
Run tests (x10)	7m 20s
Run tests (x12s)	6m 57s
Run tests (x7)	3m 44s
Run tests (x9d)	3m 3s
Run tests (x9dp)	3m 37s
Run tests (x9e)	3m 9s
Run tests (x9lite)	3m 35s
Run tests (x9lites)	3m 44s
Run tests (xlite)	3m 18s
Run tests (xlites)	3m 53s
Run builds (nv14;el18)	7m 27s
Run builds (t12)	2m 39s
Run builds (t16)	4m 32s
Run builds (t18)	4m 14s
Run builds (t8;zorro;pocket;commando8)	6m 18s
Run builds (tlite;tpro;tprov2;lr3pro)	5m 9s
Run builds (t20)	2m 28s
Run builds (tx12;tx12mk2;boxer)	4m 3s
Run builds (tx16s)	5m 53s
Run builds (x10;x10-access)	7m 27s
Run builds (x12s)	4m 14s
Run builds (x7;x7-access)	3m 44s
Run builds (x9d;x9dp;x9dp2019)	4m 5s
Run builds (x9e;x9e-hall)	3m 41s
Run builds (x9lite;x9lites)	2m 57s
Run builds (xlite;xlites)	3m 56s
	2h 56m 59s

Provide feedback