Update Button plain primary icon color (#9622)

### WHY are these changes introduced?

Fixes Shopify/archive-polaris-backlog-2024#725

### WHAT is this pull request doing?

Updates the icon color of `primary` `plain` icon only buttons

### How to 🎩
- Review in Storybook
- Ensure no regressions to `primary` `plain` `destructive` icon only
button icon color

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

@@ -348,8 +348,8 @@
  // stylelint-disable polaris/conventions/polaris/custom-property-allowed-list -- se23 temporary styles
  --pc-button-text: var(--p-color-text-inverse-subdued);
  background: var(--pc-button-color-active);
- // stylelint-enable polaris/conventions/polaris/custom-property-allowed-list
  box-shadow: var(--p-shadow-button-inset-experimental);
+ // stylelint-enable polaris/conventions/polaris/custom-property-allowed-list
  // stylelint-enable-next-line length-zero-no-unit
  &::before {
  opacity: 1;
@@ -648,6 +648,31 @@
 
  &.iconOnly {
  margin: calc(-1 * var(--p-space-1));
+
+ // stylelint-disable selector-max-combinators, max-nesting-depth, selector-max-class -- se23 temporary styles
+ path {
+ fill: var(--p-color-icon-subdued);
+ }
+
+ &:active,
+ &:hover {
+ path {
+ fill: var(--p-color-icon);
+ }
+ }
+
+ &.destructive {
+ path {
+ fill: var(--p-color-text-critical);
+ }
+ }
+
+ &.disabled {
+ path {
+ fill: var(--p-color-icon-disabled);
+ }
+ }
+ // stylelint-enable selector-max-combinators, max-nesting-depth, selector-max-class
  }
  }
 }