Bypass confirmation box for "delete user and contributions"

Summary

The "delete user and contributions" dialog prompting the admin to enter the name of the user to delete may be bypassed by hitting enter.

Steps to reproduce

• Create a test user
• As administrator, click "Delete user and contributions" button to delete the user.
• In the dialog popup, click focus into the text input field
• Hit enter

What is the current bug behavior?

The user is deleted without the "type the name" validation.

What is the expected correct behavior?

The form is not submitted unless the input field value is correct.

Results of GitLab environment info

System information
System:
Current User:	git
Using RVM:	no
Ruby Version:	2.5.3p105
Gem Version:	2.7.6
Bundler Version:1.17.3
Rake Version:	12.3.2
Redis Version:	3.2.12
Git Version:	2.18.1
Sidekiq Version:5.2.5
Go Version:	unknown

GitLab information
Version:	11.10.1
Revision:	861fe405571
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	9.6.11
URL:		<redacted>
HTTP Clone URL:	<redacted>
SSH Clone URL:	git@<redacted>:some-group/some-project.git
Using LDAP:	no
Using Omniauth:	yes
Omniauth Providers: saml

GitLab Shell
Version:	9.0.0
Repository storage paths:
- default: 	/var/opt/gitlab/git-data/repositories
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell
Git:		/opt/gitlab/embedded/bin/git