[Dropzone] Fix wonky border radius (#9166)

The border radius of the `DropZone` component was messed up. This PR
fixes that.


![dropzone-border-radius](https://user-images.githubusercontent.com/875708/236408252-cca2bdab-b9f0-42f3-9b4b-166cb7247ee7.jpg)

### 🎩 checklist

- [x] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [x] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [x] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [x] Updated the component's `README.md` with documentation changes
- [x] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

---------

Co-authored-by: Chloe Rice <chloerice@users.noreply.github.com>

.changeset/breezy-mirrors-fetch.md

@@ -0,0 +1,5 @@
+---
+'@shopify/polaris': patch
+---
+
+Fixed the border radius of `DropZone`

polaris-react/src/components/DropZone/DropZone.scss

@@ -33,7 +33,7 @@ $dropzone-stacking-order: (
   display: flex;
   justify-content: center;
   background-color: var(--p-color-bg);
-  border-radius: var(--p-border-radius-1);
+  border-radius: var(--p-border-radius-2);
 
   &::after {
     content: '';
@@ -45,7 +45,7 @@ $dropzone-stacking-order: (
     bottom: 0;
     left: 0;
     border: var(--p-border-width-1) $dropzone-border-style transparent;
-    border-radius: var(--p-border-radius-1);
+    border-radius: var(--p-border-radius-2);
     pointer-events: none;
   }
 
@@ -125,7 +125,7 @@ $dropzone-stacking-order: (
 
 .Container {
   // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
-  @include focus-ring($border-width: 1px);
+  @include focus-ring($size: 'wide', $border-width: var(--p-border-width-1));
   flex: 1;
 }
 
@@ -164,7 +164,7 @@ $dropzone-stacking-order: (
   &:not(.isDisabled) {
     .Container {
       // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
-      @include focus-ring($style: 'focused');
+      @include focus-ring($size: 'wide', $style: 'focused');
     }
   }
 }