Optimize the accordion icon (#39411)

Co-authored-by: Serhii Babakov <babakov@aweb.ua>
Co-authored-by: Julien Déramond <juderamond@gmail.com>

scss/_variables.scss

@@ -1392,8 +1392,8 @@ $accordion-icon-active-color:             $primary-text-emphasis !default;
 $accordion-icon-transition:               transform .2s ease-in-out !default;
 $accordion-icon-transform:                rotate(-180deg) !default;
 
-$accordion-button-icon:         url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='#{$accordion-icon-color}'><path fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/></svg>") !default;
-$accordion-button-active-icon:  url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='#{$accordion-icon-active-color}'><path fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/></svg>") !default;
+$accordion-button-icon:         url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none' stroke='#{$accordion-icon-color}' stroke-linecap='round' stroke-linejoin='round'><path d='M2 5L8 11L14 5'/></svg>") !default;
+$accordion-button-active-icon:  url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none' stroke='#{$accordion-icon-active-color}' stroke-linecap='round' stroke-linejoin='round'><path d='M2 5L8 11L14 5'/></svg>") !default;
 // scss-docs-end accordion-variables
 
 // Tooltips