Issue #3410681 by AkshayAdhav: Remove @nest from claro stylesheets

• /core/themes/claro/css/components/breadcrumb.pcss.css
• /core/themes/claro/css/components/card.pcss.css
• /core/themes/claro/css/components/details.pcss.css
• /core/themes/claro/css/components/form--checkbox-radio.pcss.css
• /core/themes/claro/css/components/form--managed-file.pcss.css
• /core/themes/claro/css/components/form--password-confirm.pcss.css
• /core/themes/claro/css/components/form--select.pcss.css
• /core/themes/claro/css/components/messages.pcss.css
• /core/themes/claro/css/components/page-title.pcss.css
• /core/themes/claro/css/components/shortcut.pcss.css
• /core/themes/claro/css/components/system-admin--admin-list.pcss.css
• /core/themes/claro/css/components/system-status-counter.pcss.css
• /core/themes/claro/css/components/tables.pcss.css
• /core/themes/claro/css/components/vertical-tabs.pcss.css
• /core/themes/claro/css/components/views_ui.admin.pcss.css

Closes #3410681