fix(GlDropdown): correct small button spacing

mentioned in commit 1105f022

mentioned in merge request gitlab!85750 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!2830 (merged)

mentioned in merge request status-page!499 (merged)

mentioned in merge request gitlab-docs!2600 (closed)

mentioned in merge request gitlab!85900 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!2836 (merged)

mentioned in merge request status-page!500 (merged)

mentioned in merge request gitlab-docs!2619 (merged)