PHPC-1415: Disable retryWrites for sharded cluster without replica set

Without replica set shards, retryable writes cannot be used. It must be explicitly disabled because the driver cannot detect this by its direct communication with mongos nodes.

Author: jmikola

.travis.scripts/setup_mo.sh

@@ -9,7 +9,7 @@ fi
 case $DEPLOYMENT in
   SHARDED_CLUSTER)
     ${TRAVIS_BUILD_DIR}/.travis.scripts/mo.sh ${TRAVIS_BUILD_DIR}/scripts/presets/travis/sharded_clusters/cluster.json start > /tmp/mo-result.json
-    cat /tmp/mo-result.json | tail -n 1 | php -r 'echo json_decode(file_get_contents("php://stdin"))->mongodb_uri;' > /tmp/uri.txt
+    cat /tmp/mo-result.json | tail -n 1 | php -r 'echo json_decode(file_get_contents("php://stdin"))->mongodb_uri, "/?retryWrites=false";' > /tmp/uri.txt
     ;;
   SHARDED_CLUSTER_RS)
     ${TRAVIS_BUILD_DIR}/.travis.scripts/mo.sh ${TRAVIS_BUILD_DIR}/scripts/presets/travis/sharded_clusters/cluster_replset.json start > /tmp/mo-result.json