chore: remove py_proto_library from bzlmod example (#3508)

With the py_proto_library rules removed from rules_python, rules_python
is no
longer the appropriate place to have examples for using the
py_proto_library
rules. Having such example also causes some maintenance burden, as
apparently
it incurs a nodejs dependency, which fails under newer bazel versions.

Fixes #3362

Author: rickeylev

examples/bzlmod/.bazelignore

@@ -1,3 +1,2 @@
 other_module
-py_proto_library/foo_external
 vendor

examples/bzlmod/MODULE.bazel

@@ -12,9 +12,6 @@ local_path_override(
     path = "../..",
 )
 
-# (py_proto_library specific) Add the protobuf library for well-known types (e.g. `Any`, `Timestamp`, etc)
-bazel_dep(name = "protobuf", version = "27.0", repo_name = "com_google_protobuf")
-
 # Only needed to make rules_python's CI happy. rules_java 8.3.0+ is needed so
 # that --java_runtime_version=remotejdk_11 works with Bazel 8.
 bazel_dep(name = "rules_java", version = "8.16.1")
@@ -291,11 +288,5 @@ local_path_override(
     path = "other_module",
 )
 
-bazel_dep(name = "foo_external", version = "")
-local_path_override(
-    module_name = "foo_external",
-    path = "py_proto_library/foo_external",
-)
-
 # example test dependencies
 bazel_dep(name = "rules_shell", version = "0.3.0", dev_dependency = True)