[CLOUD-95] Adjust label copy and remove beta badge from menu items

Created by: quinnkeast

In the product today, we show the Beta badge in two menu locations: the user dropdown menu next to "Your repositories," and the user settings sidebar menu, also next to "Your repositories."

Before:

From previous discussion (Figma artifact, Slack discussion with @AlicjaSuska), we decided that menu items are not the place to indicate beta status, but rather just highlight new features with the New badge. The beta status of "Repositories" is indicated in context on the repositories view, and doesn't need to be duplicated in the menus. When we include the beta badge in the menus, we add more visual noise and take away from the actual highlighted new features, without a clear value proposition.

This PR:

• Removes the Beta badge from the user dropdown menu and the user settings sidebar
• Changes the capitalization of Your Repositories → Your repositories in the user dropdown menu to match formatting elsewhere
• Changes the settings sidebar title from User Account to Account.

After: