[newauth] Enable by default

Bug: 404613530
Change-Id: If0a214fe074d7e7591b5d37417ca447525c983b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6418563
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
Commit-Queue: Allen Li <ayatane@chromium.org>

newauth.py

@@ -13,7 +13,7 @@ import scm
 
 def Enabled() -> bool:
     """Returns True if new auth stack is enabled."""
-    if not EnabledInConfig():
+    if ExplicitlyDisabled():
         return False
     if _HasGitcookies():
         _PrintGitcookiesWarning()