Remove docs-build workaround

The workaround was fixed by mkdocstrings-python 1.9.1 and pulp-docs
pinned its dependencies to >=1.9.1

pulp-docs-pin: pulp/pulp-docs#37

[noissue]

.github/workflows/scripts/build_all_docs.sh

@@ -1,11 +1,5 @@
 # This script builds the documentation site for staging-docs.pulpproject.org
 
-# TODO: this chdir move is a tmp workaround. Remove when no longer needed.
-# see: https://github.com/mkdocstrings/python/issues/145
-mkdir ../build_dir && pushd ../build_dir
-
 pip install git+https://github.com/pulp/pulp-docs.git
 pulp-docs build
-tar cvf ../pulpcore/staging-docs.pulpproject.org.tar site
-
-popd
+tar cvf staging-docs.pulpproject.org.tar site