Add a message when `CommonDBChild` item creation is refused (#21524) #41774

Job	Run time
Lint on PHP 8.4	2m 57s
Lint on PHP 8.5	2m 56s
Generate tests matrix	2s
Lint on PHP 8.2	2m 40s
E2E and web tests using latest PHP and MariaDB versions	1h 7m 11s
Test on PHP 8.5 using mariadb:11.8	47m 13s
Test on PHP 8.4 using mariadb:11.8	44m 4s
Test on PHP 8.2 using mariadb:11.8	50m 45s
Test on PHP 8.4 using mysql:8.0	53m 28s
Test on PHP 8.4 using mysql:8.4	52m 37s
Test on PHP 8.4 using percona:8.4	53m 21s
Test on PHP 8.4 using percona:8.0	53m 23s
Test on PHP 8.4 using mariadb:10.6	48m 56s
	7h 59m 33s

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