Add request specs for security policies mutations

What does this MR do and why?

In this MR we're adding missing specs for recently added security policies mutations.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #337962 (closed)

ee/app/graphql/mutations/security_policy/create_security_policy_project.rb

@@ -23,7 +23,6 @@ def resolve(args)
         project = authorized_find!(args[:project_path])
 
         result = create_project(project)
-
         return { project: nil, errors: [result[:message]] } if result[:status] == :error
 
         {