Fix documentation: how to start server for cpp tests
### Modifications
Out-of-date instructions in pulsar-client-cpp/README.md about how to start test server
@@ -202,11 +202,13 @@ ${PULSAR_PATH}/pulsar-client-cpp/tests/
# Execution
# Start standalone broker
-export PULSAR_STANDALONE_CONF=${PULSAR_PATH}/pulsar-client-cpp/tests/standalone.conf
-${PULSAR_PATH}/bin/pulsar standalone
+${PULSAR_PATH}/pulsar-test-service-start.sh
# Run the tests
${PULSAR_PATH}/pulsar-client-cpp/tests/main
+
+# When no longer needed, stop standalone broker
+${PULSAR_PATH}/pulsar-test-service-stop.sh
```
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