Windows bootstrapping: remove unneeded call to add dll to PATH (#33622)

#32942 fixed bootstrapping on Windows by having the core Spack
code explicitly add the Clingo package bin/ directory as a
DLL path.

Since then, #33400 has been merged, which ensures that the Python
module installed by the Spack `clingo` package can find the DLLs
in bin/.

Note that this only works for Spack instances which have been
bootstrapped after #33400: for installations bootstrapped before
then, you will need to run `spack clean -b` (this would only
be needed for Spack instances running on Windows).

lib/spack/spack/bootstrap.py

@@ -90,13 +90,6 @@ def _try_import_from_store(module, query_spec, query_info=None):
         ]  # type: list[str]
         path_before = list(sys.path)
 
-        # Python 3.8+ on Windows does not search dependent DLLs in PATH,
-        # so we need to manually add it using os.add_dll_directory
-        # https://docs.python.org/3/whatsnew/3.8.html#bpo-36085-whatsnew
-        if sys.version_info[:2] >= (3, 8) and sys.platform == "win32":
-            if os.path.isdir(candidate_spec.prefix.bin):
-                os.add_dll_directory(candidate_spec.prefix.bin)  # novermin
-
         # NOTE: try module_paths first and last, last allows an existing version in path
         # to be picked up and used, possibly depending on something in the store, first
         # allows the bootstrap version to work when an incompatible version is in