XWIKI-22501: Attachment progress info is lacking contrast (#3534)

* Removed the opacity that was here without a specific good reason. This solves the contrast issue and AFAIK wasn't necessary for anything
* Added a border radius to improve consistency of the skin style since `XWIKI-21334: Uniformize the rounded edges of visual elements`

xwiki-platform-core/xwiki-platform-web/xwiki-platform-web-war/src/main/webapp/resources/uicomponents/widgets/upload.css

@@ -6,6 +6,7 @@
   position: relative;
   padding: .3em 1em .3em 22px;
   background: $theme.highlightColor none 2px .8em no-repeat;
+  border-radius: 7px; /* Same value as @border-radius-base from Flamingo. */
   margin: .5em 0;
   clear: both;
   display: flex;
@@ -46,7 +47,6 @@
 }
 .progress-info {
   flex-basis: 100%;
-  opacity: 0.5;
 }
 .upload-inprogress .progress-info {
   opacity: 1;