Fix border width for the spinner (#18727)

frontend/src/metabase/components/LoadingSpinner.css

frontend/src/metabase/components/LoadingSpinner.jsx

...src/metabase/components/LoadingSpinner/LoadingSpinner.jsx

...abase/components/LoadingSpinner/LoadingSpinner.styled.jsx

frontend/src/metabase/components/LoadingSpinner/index.js

...nd/test/metabase/scenarios/dashboard/dashboard.cy.spec.js

frontend/test/metabase/scenarios/dashboard/x-rays.cy.spec.js

...tabase/scenarios/onboarding/home/activity-page.cy.spec.js

...se/scenarios/onboarding/search/recently-viewed.cy.spec.js

...se/scenarios/onboarding/search/search-typehead.cy.spec.js

frontend/test/metabase/scenarios/question/filter.cy.spec.js

frontend/test/metabase/scenarios/question/nulls.cy.spec.js

...ns/13263-postgres-show-row-details-on-pk-click.cy.spec.js