tests: Fix a bug in sync_cmd_get_more
tests: Fix a bug in sync_cmd_get_more

Use the full namespace for mongo_sync_cmd_get_more(), instead of only
the database name. This makes the test pass when using replicasets.

Signed-off-by: Gyorgy Demarcsek <5752bd0ba17473954fd76dcff037ae00724791c0@icloud.com>

algernon/libmongo-client,algernon/libmongo-client,algernon/libmongo-client