remove the python package reuse example (#4262)

Author: davidsanfal

reference/tools/system/pipenv.rst

@@ -8,23 +8,19 @@ PipEnv
 
 .. important::
 
-    This is **only** for executable Python packages.
-    This approach doesn't work for Python library packages that you would typically use via ``import``.
+    This is **only** for executable Python packages and its Python dependencies.
+    This approach doesn't work for Python library packages that you would typically use via ``import`` inside your recipe.
 
 The ``PipEnv`` helper installs executable Python packages with **pip** inside a dedicated virtual environment (**venv**),
 keeping them isolated so they don't interfere with system packages or the Conan package itself.
+It is designed to use a Python CLI tool inside a recipe during the build step.
 
 .. currentmodule:: conan.tools.system
 
 .. autoclass:: PipEnv
     :members:
     :inherited-members:
 
-It is designed to be used in two different ways:
-
-1. Using a Python CLI tool inside a recipe.
-2. Use a tool installed as a Python package locally and reuse it in other recipes.
-
 Using a Python package in a recipe
 ----------------------------------
 
@@ -82,104 +78,3 @@ If we run a ``conan build`` we can see how our Python package is installed when
     conanfile.py (pip_install/0.1): Calling build()
     conanfile.py (pip_install/0.1): RUN: meson --version
     1.9.1
-
-
-Use a tool installed as a Python package and reuse it in other recipes
-----------------------------------------------------------------------
-
-In this case, we want to locally embed the installation of a tool using pip and reuse it as a conan recipe.
-
-To do this, we need to install our tool using ``PipEnv.install()``, but in this case we will specify that we want it
-to create the virtualenv in the ``package_folder``.
-
-In this case, we don't need to call the ``PipEnv.generate()`` method because we're not going to use the tool within this recipe.
-We just want to make it reusable.
-
-When creating a recipe to encapsulate a tool installed with Python, several things must be taken into account:
-
-- The packages are installed in the `finalize()` method. This ensures that the contents of the package folder do not change when the installed tools are run,
-  because Python packages normally generate certain files when executed.
-- We will add the properties ``build_policy = "missing"`` and ``upload_policy = "skip"`` to the recipe to ensure that it is only used locally
-  and the resulting package will not be uploaded. This is important because **the generated package only works on the machine on which it was generated**
-  due to how Python virtual environments work.
-
-..  code-block:: python
-    :caption: conanfile.py
-
-    from conan import ConanFile
-    from conan.tools.system import PipEnv
-    from conan.tools.layout import basic_layout
-
-
-    class MesonPipPackage(ConanFile):
-        name = "pip_meson"
-        version = "0.1"
-        build_policy = "missing"
-        upload_policy = "skip"
-
-        def layout(self):
-            basic_layout(self)
-
-        def finalize(self):
-            PipEnv(self, self.package_folder).install(["meson==1.9.1"])
-
-        def package_info(self):
-            python_env_bin = PipEnv(self, self.package_folder).bin_dir
-            self.buildenv_info.prepend_path("PATH", python_env_bin)
-
-.. code-block:: bash
-
-    $ conan create . --version 0.1
-
-  -------- Installing package pip_meson/0.1 (1 of 1) --------
-  ...
-  pip_meson/0.1: Calling finalize()
-  pip_meson/0.1: RUN: /Users/user/.conan2/p/b/pip_m19e45e29ec612/f/pip_venv_pip_meson/bin/python -m pip install --disable-pip-version-check meson==1.9.1
-  Collecting meson==1.9.1
-    Using cached meson-1.9.1-py3-none-any.whl.metadata (1.8 kB)
-  Using cached meson-1.9.1-py3-none-any.whl (1.0 MB)
-  Installing collected packages: meson
-  Successfully installed meson-1.9.1
-
-..  code-block:: python
-    :caption: conanfile.py
-
-    from conan import ConanFile
-
-
-    class PipBuildPackage(ConanFile):
-        name = "reuse_pip"
-        version = "0.1"
-
-        def requirements(self):
-            self.tool_requires("pip_meson/0.1")
-
-        def build(self):
-            self.run("meson --version")
-
-.. code-block:: bash
-
-    $ conan build .
-
-    ======== Computing dependency graph ========
-    Graph root
-        conanfile.py (reuse_pip/0.1): /Users/user/reuse_pip/conanfile.py
-    Build requirements
-        pip_meson/0.1#0f1f4d0fc28b2ef5951f42131ede4f99 - Cache
-
-    ======== Computing necessary packages ========
-    Build requirements
-        pip_meson/0.1#0f1f4d0fc28b2ef5951f42131ede4f99:da39a3ee5e6b4b0d3255bfef95601890afd80709#0ba8627bd47edc3a501e8f0eb9a79e5e - Cache
-
-    ======== Installing packages ========
-    pip_meson/0.1: Already installed! (1 of 1)
-    pip_meson/0.1: Finalized folder /Users/user/.conan2/p/b/pip_m19e45e29ec612/f
-
-    ======== Finalizing install (deploy, generators) ========
-    conanfile.py (reuse_pip/0.1): Generating aggregated env files
-    conanfile.py (reuse_pip/0.1): Generated aggregated env files: ['conanbuild.sh', 'conanrun.sh']
-
-    ======== Calling build() ========
-    conanfile.py (reuse_pip/0.1): Calling build()
-    conanfile.py (reuse_pip/0.1): RUN: meson --version
-    1.9.1