Uninstall merlin-sdk before installing pyfunc/batch dependencies (#507)

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**What this PR does / why we need it**:
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If user has a direct or indirect dependency on merlin-sdk on their
pyfunc or batch job's conda.yaml, that merlin-sdk version is the one
that will be used to run the pyfunc or batch job, ignoring the local
merlin-sdk. By uninstalling it before installing the pyfunc or batch job
dependencies, we make sure to always use the local merlin-sdk version.

**Which issue(s) this PR fixes**:
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Fixes pyfunc/batch job running old version of merlin

**Does this PR introduce a user-facing change?**:
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NONE
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**Checklist**

- [ ] Added unit test, integration, and/or e2e tests
- [x] Tested locally
- [ ] Updated documentation
- [ ] Update Swagger spec if the PR introduce API changes
- [ ] Regenerated Golang and Python client if the PR introduce API
changes

python/batch-predictor/docker/app.Dockerfile

@@ -31,7 +31,7 @@ COPY --chown=${UID}:${GID} batch-predictor ${HOME}/merlin-spark-app
 COPY --chown=${UID}:${GID} sdk ${HOME}/sdk
 ENV SDK_PATH=${HOME}/sdk
 
-RUN /bin/bash -c ". activate merlin-model && pip install -r ${HOME}/merlin-spark-app/requirements.txt"
+RUN /bin/bash -c ". activate merlin-model && pip uninstall -y merlin-sdk && pip install -r ${HOME}/merlin-spark-app/requirements.txt"
 
 # Download and dry-run user model artifacts and code
 ARG MODEL_ARTIFACTS_URL

python/pyfunc-server/docker/Dockerfile

@@ -32,7 +32,7 @@ COPY sdk /sdk
 ENV SDK_PATH=/sdk
 
 WORKDIR /pyfunc-server
-RUN /bin/bash -c ". activate merlin-model && pip install -r /pyfunc-server/requirements.txt"
+RUN /bin/bash -c ". activate merlin-model && pip uninstall -y merlin-sdk && pip install -r /pyfunc-server/requirements.txt"
 
 # Download and dry-run user model artifacts and code
 ARG MODEL_ARTIFACTS_URL