fix: Local tarball Docker container is missing zstd dependency (#32135)

RELEASING/Dockerfile.from_local_tarball

@@ -30,7 +30,7 @@ RUN apt-get install -y apt-transport-https apt-utils
 # Install superset dependencies
 # https://superset.apache.org/docs/installation/installing-superset-from-scratch
 RUN apt-get install -y build-essential libssl-dev \
-    libffi-dev python3-dev libsasl2-dev libldap2-dev libxi-dev chromium
+    libffi-dev python3-dev libsasl2-dev libldap2-dev libxi-dev chromium zstd
 
 # Install nodejs for custom build
 # https://nodejs.org/en/download/package-manager/
@@ -64,7 +64,7 @@ RUN pip install --upgrade setuptools pip \
 RUN flask fab babel-compile --target superset/translations
 
 ENV PATH=/home/superset/superset/bin:$PATH \
-    PYTHONPATH=/home/superset/superset/:$PYTHONPATH \
+    PYTHONPATH=/home/superset/superset/ \
     SUPERSET_TESTENV=true
 COPY from_tarball_entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]