Mount the pyenv directory in the same location in the build and base stages

As pyenv shims are bash scripts containing the pyenv root dir, the pyenv directory must be mounted in the same location in both build stages.

airflow@cae536f00368:/opt/airflow$ cat /pyenv/shims/python3.10
set -e
[ -n "$PYENV_DEBUG" ] && set -x

program="${0##*/}"

export PYENV_ROOT="/tmp/pyenv"
exec "/tmp/pyenv/libexec/pyenv" exec "$program" "$@"
airflow@cae536f00368:/opt/airflow$ python3.10
/pyenv/shims/python3.10: line 8: /tmp/pyenv/libexec/pyenv: No such file or directory

Signed-off-by: Balthazar Rouberol brouberol@wikimedia.org Bug: T379266