New setting for TTL for the dependency proxy

...s/settings/group/components/dependency_proxy_settings.vue

...gistries/settings/group/components/group_settings_app.vue

..._registries/settings/group/components/settings_titles.vue

..._dependency_proxy_image_ttl_group_policy.mutation.graphql

...graphql/queries/get_group_packages_settings.query.graphql

...d_registries/settings/group/graphql/utils/cache_update.js

...ries/settings/group/graphql/utils/optimistic_responses.js

locale/gitlab.pot

...oup/components/__snapshots__/settings_titles_spec.js.snap

...ttings/group/components/dependency_proxy_settings_spec.js

...ries/settings/group/components/group_settings_app_spec.js

...istries/settings/group/components/settings_titles_spec.js

...gistries/settings/group/graphl/utils/cache_update_spec.js

.../settings/group/graphl/utils/optimistic_responses_spec.js

...ntend/packages_and_registries/settings/group/mock_data.js