VPN-6220: Fix MacOS Taskcluster jobs after bad squash/merge (#9168)

taskcluster/scripts/build/macos_build.sh

@@ -38,17 +38,8 @@ export LANG=en_US.utf-8
 export PYTHONIOENCODING="UTF-8"
 
 print Y "Installing conda"
-chmod +x ${MOZ_FETCHES_DIR}/miniconda.sh
-bash ${MOZ_FETCHES_DIR}/miniconda.sh -b -u -p ${TASK_HOME}/miniconda
-source ${TASK_HOME}/miniconda/bin/activate
-
-
-print Y "Installing provided conda env..."
-# TODO: Check why --force is needed if we install into TASK_HOME?
-conda env create --force -f env.yml
-conda activate VPN
-./scripts/macos/conda_install_extras.sh
-conda info
+source ${TASK_WORKDIR}/fetches/bin/activate
+conda-unpack
 
 # Conda Cannot know installed MacOS SDK'S
 # and as we use conda'provided clang/llvm