Use default python in PATH for circleci windows bot. NFC (#1609)

`C:\Python312\python.exe` is already in the path by default.

We no longer need to set this special path or environment variable. In
fact this code was doing nothing since it was adding the end of the PATH
so the system python was already coming first.

test/test.bat

@@ -1,5 +1,4 @@
 :: equivalent of test.sh as windows bat file
-set PATH=%PATH%;%PYTHON_BIN%
 CALL emsdk install latest
 CALL emsdk activate latest
 CALL emsdk_env.bat