Pin python-confluent-kafka to 2.4.0

Current would be 2.5.0, and sqlite3 import failed with it.
Pin it to the version of the last prompt-service release 4.1.2.

Check if python-confluent-kafka already exists, if not, install
the fixed version.

rubin-env 9 will come with a python-confluent-kafka.

base/Dockerfile

@@ -1,10 +1,12 @@
 ARG STACK_TAG=d_latest
 FROM lsstsqre/centos:${STACK_TAG}
 ENV PYTHONUNBUFFERED True
+ARG kafka=python-confluent-kafka
 RUN source /opt/lsst/software/stack/loadLSST.bash \
     && mamba install -y \
         flask \
         gunicorn \
-        python-confluent-kafka \
+    && (mamba list ${kafka} | grep ${kafka} || \
+        mamba install -y "${kafka}=2.4.0" ) \
     && pip install --no-input \
         cloudevents