Improve admin page layout (#37706)

e2e/test/scenarios/admin-2/people/people.cy.spec.js

e2e/test/scenarios/embedding/embedding-smoketests.cy.spec.js

...adata/components/MetadataEditor/MetadataEditor.styled.tsx

...del/metadata/components/MetadataEditor/MetadataEditor.tsx

...omponents/MetadataFieldSettings/MetadataFieldSettings.tsx

...del/metadata/components/MetadataHeader/MetadataHeader.tsx

...data/components/MetadataSchemaList/MetadataSchemaList.tsx

...model/metadata/components/MetadataTable/MetadataTable.tsx

...onents/MetadataTableColumn/MetadataTableColumn.styled.tsx

...ta/components/MetadataTableColumn/MetadataTableColumn.tsx

...nents/MetadataTableColumnList/MetadataTableColumnList.tsx

...tadata/components/MetadataTableList/MetadataTableList.tsx

...d/src/metabase/admin/people/containers/AdminPeopleApp.tsx

...settings/app/components/SettingsEditor/SettingsEditor.jsx

...base/admin/settings/components/SettingsSetting.styled.tsx

.../src/metabase/admin/tasks/components/Help/Help.styled.tsx

...src/metabase/admin/tasks/containers/JobInfoApp.styled.tsx

...d/src/metabase/admin/tasks/containers/TasksApp.styled.tsx

...rc/metabase/admin/tasks/containers/TroubleshootingApp.jsx

frontend/src/metabase/components/AdminLayout/AdminLayout.jsx