test: fix "Catalog numbers should reject invalid values".

Relate to #1001
Fix #546

Author: php-coder

src/test/robotframework/series/creation/validation-user.robot

@@ -37,7 +37,6 @@ Create series with an empty image
 	Element Text Should Be  id=image.errors  File must not be empty
 
 Catalog numbers should reject invalid values
-	[Tags]      unstable
 	[Template]  Invalid Catalog Numbers Should Be Rejected
 	t
 	t,t
@@ -74,6 +73,7 @@ Invalid Catalog Numbers Should Be Rejected
 	# invisible (because link is toggling the visibility and when there are
 	# errors, fields are visible from the begining).
 	Go To                          ${SITE_URL}/series/add
+	Disable Client Validation
 	Click Element                  id=add-catalog-numbers-link
 	# we should wait until all 4 fields with class js-catalogs-info will be
 	# visible but for simplicity we just check that the last field is visible