Stats: fix summary locations selector style (#98504)

* Stats: fix locations summary style

They were using the same classes but lacking attributes that were
included from the modernized mixin.

* Use all available space for the locations selector

client/my-sites/stats/summary/style.scss

@@ -1,6 +1,9 @@
 @import "@wordpress/base-styles/breakpoints";
+@import "../modernized-mixins";
 
 .stats-summary-view {
+	@include segmented-controls;
+
 	.highlight-cards-heading {
 		@media (min-width: 661px) and (max-width: 1380px) {
 			margin-left: 32px;
@@ -43,3 +46,7 @@
 		}
 	}
 }
+
+.stats-module-locations__tabs {
+	width: 100%;
+}