Fix specificity for buttons with outline style and background colors (#…

…24599)

When the .wp-block-button.is-style-outline .wp-block-button_link
selector was added, its specificity (030) overrode existing
theme selectors that had 020 specificity.

packages/block-library/src/button/style.scss

@@ -47,7 +47,7 @@ $blocks-button__height: 56px;
 	border-radius: 0 !important;
 }
 
-.wp-block-button.is-style-outline .wp-block-button__link,
+.is-style-outline .wp-block-button__link,
 .wp-block-button__link.is-style-outline {
 	color: $dark-gray-700;
 	background-color: transparent;