fix(GlToggle): Enable flex-grow-1 to ensure backwards compatibility

mentioned in commit a054b8ca

mentioned in merge request status-page!833 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!168 (merged)

mentioned in merge request gitlab!126562 (merged)

mentioned in merge request gitlab-docs!4074 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3432 (merged)

mentioned in merge request gitlab!128113 (closed)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3479 (merged)