Set empty value for disabled inputs

ee/app/views/admin/application_settings/_repository_size_limit_setting.html.haml

@@ -9,6 +9,6 @@
       = _('Includes LFS objects. It can be overridden per group, or per project. 0 for unlimited.')
       = link_to _('Learn more.'), help_page_path('user/admin_area/settings/account_and_limit_settings'), target: '_blank', rel: 'noopener noreferrer'
   - else
-    = form.number_field :disabled_repository_size_limit, value: '0', class: 'form-control gl-form-input', disabled: true
+    = form.number_field :disabled_repository_size_limit, value: '', class: 'form-control gl-form-input', disabled: true
     %span.form-text.text-muted
       = render 'shared/registration_features_discovery_message', license: @license

ee/app/views/shared/_repository_size_limit_setting.html.haml

@@ -12,6 +12,6 @@
       %span.form-text.text-muted#repository_size_limit_help_block
         = is_project ? size_limit_message(@project) : size_limit_message_for_group(@group)
     - else
-      = form.number_field :disabled_repository_size_limit, value: '0', class: 'form-control', disabled: true
+      = form.number_field :disabled_repository_size_limit, value: '', class: 'form-control', disabled: true
       %span.form-text.text-muted
         = render 'shared/registration_features_discovery_message', license: @license