fix(ListBox): correctly position menu chevron (#8155)

* Revert "fix(ListBox): add top positioning to chevron (#7990)"

This reverts commit 460bf18.

* fix(dropdown): remove overwriting mixin

* refactor(dropdown): remove redundant rule

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/components/src/components/dropdown/_dropdown.scss

@@ -66,9 +66,6 @@
 
   // Menu's triggering element updated to button with Downshift v5 upgrade
   .#{$prefix}--dropdown .#{$prefix}--list-box__field {
-    @include button-reset;
-
-    padding: 0 rem(48px) 0 rem(16px);
     text-align: left;
 
     // Windows, Firefox HCM Fix

packages/components/src/components/list-box/_list-box.scss

@@ -395,7 +395,6 @@ $list-box-menu-width: rem(300px);
     @include button-reset($width: false);
 
     position: absolute;
-    top: $carbon--spacing-03;
     right: $carbon--spacing-05;
     display: flex;
     align-items: center;