fix(input-group): custom-file with validation (#33239)

Author: ffoodd

scss/_input-group.scss

@@ -52,12 +52,14 @@
     align-items: center;
 
     &:not(:last-child) .custom-file-label,
+    &:not(:last-child) .custom-file-label::after { @include border-right-radius(0); }
     &:not(:first-child) .custom-file-label { @include border-left-radius(0); }
   }
 
   &:not(.has-validation) {
     > .form-control:not(:last-child),
     > .custom-select:not(:last-child),
+    > .custom-file:not(:last-child) .custom-file-label,
     > .custom-file:not(:last-child) .custom-file-label::after {
       @include border-right-radius(0);
     }
@@ -66,6 +68,7 @@
   &.has-validation {
     > .form-control:nth-last-child(n + 3),
     > .custom-select:nth-last-child(n + 3),
+    > .custom-file:nth-last-child(n + 3) .custom-file-label,
     > .custom-file:nth-last-child(n + 3) .custom-file-label::after {
       @include border-right-radius(0);
     }