[FIX] project: remove space between email alias and project title

Steps:
- Install project.
- Go to settings and select Custom Email Servers.
- Add alias domain.
- Then go to the project.
- Create a new project.
- The gap between the email alias and project title is too much.

Issue:
-When we create a new project the gap between the email alias and project name is too
 much when only the project is installed and there are no options to display. 

Cause:
-The "margin-top-4" taking much space.

Fix:
-After this commit the space between email alias and project name is decreased
 by changing the space.

task-3550638

closes odoo/odoo#153277

X-original-commit: b01b2f2f4d2e31648e3c98b8991eaafc886ca542
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>

addons/project/views/project_project_views.xml

@@ -336,7 +336,7 @@
                     </div>
                     <field name="user_id" invisible="1"/>
                     <div class="row o_settings_container"/>
-                    <div name="alias_def" class="mt-4" colspan="2">
+                    <div name="alias_def" class="mt-2" colspan="2">
                         <label for="alias_name" string="Create tasks by sending an email to"/>
                         <span>
                             <field name="alias_name" placeholder="e.g. office-party"/>@