[FIX] mail: Fix the issue with activity widget dropdown scrollbar

This commit fixes the issue with dropdown of activity in kanban.
The activity dropdown was cut with document inspectorbar in document
kanban view due to data-boundry window on dropdown.

Note:
Dropdown of list activity was cut on the list view and to fix that
commit[1] was done but it has side effect on document kanban view.
another fix was done in commit[2] so now commit[1] is not useful so
here revert that commit.

[1] - https://github.com/odoo/odoo/commit/cef57b930b27cb487973f251797c93ea3967a5b3
[2] - https://github.com/odoo/odoo/commit/a98f0621169144f53f4ebc9361f3b7c6b60556c8



closes odoo/odoo#60529

Taskid: 2336146
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/mail/static/src/xml/web_kanban_activity.xml

@@ -3,7 +3,7 @@
 
 <t t-name="mail.KanbanActivity">
     <div class="o_kanban_inline_block dropdown o_mail_activity">
-        <a class="dropdown-toggle o-no-caret o_activity_btn" data-toggle="dropdown" role="button" data-boundary="window">
+        <a class="dropdown-toggle o-no-caret o_activity_btn" data-toggle="dropdown" role="button">
             <!-- span classes are generated dynamically (see _render) -->
             <span t-att-title="widget.selection[widget.activityState]" role="img" t-att-aria-label="widget.selection[widget.activity_state]"/>
        </a>