Fix input height border (#25331)

When changing `$input-border-width`, `$input-height-border` does not change and `select.form-control` `custom-select` `custom-file` will still have `$input-height` which is resolved from `$input-btn-border-width`

This will work in cases when want controls with border, and buttons without.

Temporary fix will be to override 2 variables

```
$input-border-width: 2px !default;

// which is
// $input-height-border: $input-btn-border-width * 2 !default;
$input-height-border: $input-border-width * 2 !default;
```

scss/_variables.scss

@@ -412,7 +412,7 @@ $input-focus-box-shadow:                $input-btn-focus-box-shadow !default;
 
 $input-placeholder-color:               $gray-600 !default;
 
-$input-height-border:                   $input-btn-border-width * 2 !default;
+$input-height-border:                   $input-border-width * 2 !default;
 
 $input-height-inner:                    ($font-size-base * $input-btn-line-height) + ($input-btn-padding-y * 2) !default;
 $input-height:                          calc(#{$input-height-inner} + #{$input-height-border}) !default;