Update to Bootstrap5.1 (#35197)

.../src/Areas/Identity/Pages/V5/Account/ExternalLogin.cshtml

...src/Areas/Identity/Pages/V5/Account/ForgotPassword.cshtml

...ntity/UI/src/Areas/Identity/Pages/V5/Account/Login.cshtml

...I/src/Areas/Identity/Pages/V5/Account/LoginWith2fa.cshtml

...as/Identity/Pages/V5/Account/LoginWithRecoveryCode.cshtml

...as/Identity/Pages/V5/Account/Manage/ChangePassword.cshtml

...dentity/Pages/V5/Account/Manage/DeletePersonalData.cshtml

.../Areas/Identity/Pages/V5/Account/Manage/Disable2fa.cshtml

...I/src/Areas/Identity/Pages/V5/Account/Manage/Email.cshtml

...entity/Pages/V5/Account/Manage/EnableAuthenticator.cshtml

...tity/Pages/V5/Account/Manage/GenerateRecoveryCodes.cshtml

...I/src/Areas/Identity/Pages/V5/Account/Manage/Index.cshtml

...reas/Identity/Pages/V5/Account/Manage/PersonalData.cshtml

...dentity/Pages/V5/Account/Manage/ResetAuthenticator.cshtml

...Areas/Identity/Pages/V5/Account/Manage/SetPassword.cshtml

...as/Identity/Pages/V5/Account/Manage/_StatusMessage.cshtml

...ty/UI/src/Areas/Identity/Pages/V5/Account/Register.cshtml

.../Identity/Pages/V5/Account/ResendEmailConfirmation.cshtml

.../src/Areas/Identity/Pages/V5/Account/ResetPassword.cshtml

...src/Areas/Identity/Pages/V5/Account/_StatusMessage.cshtml