Remove auto-detection of Python toolchain from MODULE.bazel

since it affects downstream users

The correct solution appears to be
https://rules-python.readthedocs.io/en/stable/toolchains.html#library-modules-with-dev-only-python-usage

This change also includes a workaround for the new mechanism creating
paths that are too long for Windows to handle.

Fixes #4581

PiperOrigin-RevId: 657706984
Change-Id: I8ae6b9e5efeb7629d79d14e7d4d3889876282d17

ci/windows-presubmit.bat

@@ -46,8 +46,13 @@ RMDIR /S /Q cmake_msvc2022
 :: ----------------------------------------------------------------------------
 :: Bazel
 
+:: The default home directory on Kokoro is a long path which causes errors
+:: because of Windows limitations on path length.
+:: --output_user_root=C:\tmp causes Bazel to use a shorter path.
 SET BAZEL_VS=C:\Program Files\Microsoft Visual Studio\2022\Community
-%BAZEL_EXE% test ... ^
+%BAZEL_EXE% ^
+  --output_user_root=C:\tmp ^
+  test ... ^
   --compilation_mode=dbg ^
   --copt=/std:c++14 ^
   --copt=/WX ^