Replace contain-floats with govuk-clearfix

Author: Vanita Barrett

app/assets/stylesheets/helpers/_publisher-metadata-with-logo.scss

@@ -2,7 +2,7 @@
 // roll out the combination of metadata + logo across
 // formats so they may ultimately become component styles.
 .metadata-logo-wrapper {
-  @extend %contain-floats;
+  @include govuk-clearfix;
   border-top: 1px solid $border-colour;
   margin-left: govuk-spacing(3);
   margin-right: govuk-spacing(3);