Revert "Bump setuptools from 67.6.0 to 70.0.0" (#17455)

Reverts #17448

We hit a bug when deploying with synctl:

```
Traceback (most recent call last):
  File "/home/synapse/env-python311/bin/synctl", line 33, in <module>
    sys.exit(load_entry_point('matrix-synapse', 'console_scripts', 'synctl')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/bin/synctl", line 25, in importlib_load_entry_point
    return next(matches).load()
           ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/importlib/metadata/__init__.py", line 202, in load
    module = import_module(match.group('module'))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/synapse/src/synapse/_scripts/synctl.py", line 37, in <module>
    from synapse.config import find_config_files
  File "/home/synapse/src/synapse/config/__init__.py", line 22, in <module>
    from ._base import ConfigError, find_config_files
  File "/home/synapse/src/synapse/config/_base.py", line 49, in <module>
    import pkg_resources
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 3282, in <module>
    @_call_aside
     ^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 3266, in _call_aside
    f(*args, **kwargs)
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 3295, in _initialize_master_working_set
    working_set = _declare_state('object', 'working_set', WorkingSet._build_master())
                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 589, in _build_master
    ws.require(__requires__)
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 926, in require
    needed = self.resolve(parse_requirements(requirements))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 787, in resolve
    dist = self._resolve_dist(
           ^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 816, in _resolve_dist
    env = Environment(self.entries)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 1014, in __init__
    self.scan(search_path)
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 1046, in scan
    for dist in find_distributions(item):
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 2091, in find_on_path
    yield from factory(fullpath)
               ^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 2183, in resolve_egg_link
    return next(dist_groups, ())
           ^^^^^^^^^^^^^^^^^^^^^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 2179, in <genexpr>
    resolved_paths = (
                     ^
  File "/home/synapse/env-python311/lib/python3.11/site-packages/pkg_resources/__init__.py", line 2167, in non_empty_lines
    for line in _read_utf8_with_fallback(path).splitlines():
                ^^^^^^^^^^^^^^^^^^^^^^^^
NameError: name '_read_utf8_with_fallback' is not defined
```