[newauth] Enable by default (reland) (include bots)

Originally
https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6418563

Bug: 404613530
Bug: 408427309
Change-Id: Ida2663110c8e2d4dbd50589bd88e81edb66a9c81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6440133
Reviewed-by: Gavin Mak <gavinmak@google.com>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
Commit-Queue: Allen Li <ayatane@chromium.org>

newauth.py

@@ -35,8 +35,6 @@ def SwitchedOn() -> bool:
 
 def Default() -> bool:
     "Returns default enablement status for new auth stack."
-    if os.getenv('SWARMING_BOT_ID'):
-        return False
     return True