fix(windows): drop duplicate creationflags kwarg in LocalEnvironment._run_bash

Commits 8bf09455d (Grogger, explicit creationflags=) and 95683c028
(nekwo, **_popen_kwargs via windows_hide_flags()) landed 77 minutes
apart and both injected creationflags into the same subprocess.Popen
call. nekwo's commit correctly replaced the explicit line in
tools/process_registry.py but only added the kwargs spread in
tools/environments/local.py -- leaving creationflags specified twice.

Result on Windows: every LocalEnvironment.init_session() raised
"subprocess.Popen() got multiple values for keyword argument
'creationflags'" and fell back to bash -l per command (much slower --
bashrc runs on every shell invocation).

Drop the explicit line so **_popen_kwargs is the single source.

tools/environments/local.py

@@ -532,7 +532,6 @@ class LocalEnvironment(BaseEnvironment):
             stderr=subprocess.STDOUT,
             stdin=subprocess.PIPE if stdin_data is not None else subprocess.DEVNULL,
             preexec_fn=None if _IS_WINDOWS else os.setsid,
-            creationflags=subprocess.CREATE_NO_WINDOW if _IS_WINDOWS else 0,
             cwd=_popen_cwd,
             **_popen_kwargs,
         )