fix: create Python symlink only during builds, and clean it up after (#2721)

* fix: create Python symlink only during builds, and clean it up after

Previously in b9ddcd5bbd this was created
during configuration, and the symlink persisted indefinitely. This
causes problems with many tools that do not expect a codebase to include
symlinks to external absolute paths.

This PR largely reverts that commit, and instead writes the path to
link to into the config, and then creates the symlink only temporarily
during the build process, always deleting it afterwards.

* assert install_path == self.output, f"{install_path} != {self.output}"

---------

Co-authored-by: Christian Clauss <cclauss@me.com>

test/test-configure-python.js

@@ -16,9 +16,7 @@ const configure = requireInject('../lib/configure', {
     mkdir: function (dir, options, cb) { cb() },
     promises: {
       writeFile: function (file, data) { return Promise.resolve(null) }
-    },
-    unlink: function (path, cb) { cb() },
-    symlink: function (target, path, cb) { cb() }
+    }
   }
 })