fix(GlDisclosureDropdown): Add spacing after loading icon

mentioned in commit 0ed87c3f

mentioned in merge request status-page!903

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!991 (merged)

mentioned in merge request gitlab!166552 (merged)

mentioned in merge request gitlab!166770 (closed)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!4067 (closed)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!349 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!51 (merged)