fix(button): remove unused theme prop for outline focus style

Author: desig9stein

projects/igniteui-angular/src/lib/core/styles/themes/schemas/light/_button.scss

@@ -80,7 +80,7 @@ $material-flat-button: extend(
 
 /// @type {Map}
 /// @prop {Map} border-color [igx-color: ('secondary', 500)] - The outline color of the button.
-/// @prop {Map} focus-border-color [igx-color: ('grays', 300)] - The focused border color of the button.
+/// @prop {Map} focus-border-color [igx-color: ('secondary', 500)] - The focused border color of the button.
 /// @prop {Map} disabled-border-color [igx-color: ('grays', 300)] - The disabled focused border color of the button.
 /// @requires {function} extend
 /// @requires {Map} $material-flat-button
@@ -90,11 +90,11 @@ $material-outlined-button: extend(
         selector: '[igxButton="outlined"], .igx-button--outlined',
 
         border-color: (
-            igx-color: ('secondary', 300)
+            igx-color: ('secondary', 500)
         ),
 
         focus-border-color: (
-            igx-color: ('grays', 300)
+            igx-color: ('secondary', 500)
         ),
 
         disabled-border-color: (