[FIX] note: use calendar icon when setting the reminder date in systray

Specifications :

 * clock icon is generally used for datetime;
 * calendar icon is generally used for date;
 * as we set the reminder date in the systray let us use the calendar
   icon in the systray in the reminder section;
 * please also remove the extra margin bottom of note when entering a
   new reminder, it makes @est-odoo very sad;

This commit is linked to task ID 1882545 and PR #26797.

addons/note/static/src/scss/note.scss

@@ -37,6 +37,7 @@
             display: flex;
             p {
                 flex: 1 1 auto;
+                margin-bottom: 0px;
             }
         }
         .o_note_save {
@@ -60,4 +61,7 @@
             }
         }
     }
+    .o_note_set_datetime {
+        color: $text-muted;
+    }
 }

addons/note/static/src/xml/systray.xml

@@ -14,8 +14,8 @@
                         <span class="o_preview_name"><strong>Add a note</strong></span>
                         <div class="o_note_datetime"/>
                         <span class="ml4">
-                            <a class="o_note_set_datetime text-muted">
-                                <span class="fa fa-clock-o" role="img" aria-label="Set date and time" title="Set date and time"/>
+                            <a class="o_note_set_datetime">
+                                <span class="fa fa-calendar" role="img" aria-label="Set date and time" title="Set date and time"/>
                             </a>
                         </span>
                     </div>