ui: Replenish the missing ‘PageIsSignUp’ in sign up view (#11390)

Signed-off-by: a1012112796 <1012112796@qq.com>

routers/user/auth.go

@@ -1028,6 +1028,7 @@ func SignUp(ctx *context.Context) {
 	ctx.Data["RecaptchaURL"] = setting.Service.RecaptchaURL
 	ctx.Data["CaptchaType"] = setting.Service.CaptchaType
 	ctx.Data["RecaptchaSitekey"] = setting.Service.RecaptchaSitekey
+	ctx.Data["PageIsSignUp"] = true
 
 	//Show Disabled Registration message if DisableRegistration or AllowOnlyExternalRegistration options are true
 	ctx.Data["DisableRegistration"] = setting.Service.DisableRegistration || setting.Service.AllowOnlyExternalRegistration
@@ -1045,6 +1046,7 @@ func SignUpPost(ctx *context.Context, cpt *captcha.Captcha, form auth.RegisterFo
 	ctx.Data["RecaptchaURL"] = setting.Service.RecaptchaURL
 	ctx.Data["CaptchaType"] = setting.Service.CaptchaType
 	ctx.Data["RecaptchaSitekey"] = setting.Service.RecaptchaSitekey
+	ctx.Data["PageIsSignUp"] = true
 
 	//Permission denied if DisableRegistration or AllowOnlyExternalRegistration options are true
 	if setting.Service.DisableRegistration || setting.Service.AllowOnlyExternalRegistration {