[FIX] web: remove dropdown-menu minimum width

This line was initially introduced to handle legacy dropdowns
inconsistencies, but it's no longer necessary.

task-2579123

addons/web/static/src/core/dropdown/dropdown.scss

@@ -1,7 +1,6 @@
 // = Default Boostrap Classes customizations
 // ----------------------------------------------------------------------------
 .dropdown-menu {
-  min-width: 100%;
   max-height: 70vh;
   overflow: auto;
   background-clip: border-box;