Remove BFormRadioGroup from GlFormRadioGroup

BootstrapVue props we should support

• aria-invalid
• checked
• disabled
• id
• name
• options
• required
• stacked
• state

BootstrapVue props we should consider not supporting

https://gitlab-org.gitlab.io/frontend/bootstrapvue-component-usage-breakdown/components.json can be used as a starting point to see if the prop is used, but should not be considered an exhaustive list (it does not check https://gitlab.com/gitlab-org/customers-gitlab-com/ or Switchboard, please do this manually). We should weigh the pros and cons of supporting each prop individually.

• autofocus
• button-variant
• buttons
• disabled-field
• form
• html-field
• plain
• size
• text-field
• value-field
• validated

BootstrapVue slots we should support

• default
• first

BootstrapVue events we should support

• change
• input