Unchecked dynamic_cast

If the dynamic_cast fails, a null pointer dereference will occur; if the dynamic_cast cannot fail, using static_cast instead offers better performance. Dynamic_cast may fail and return null if the type cast is incompatible
/data/mci/8df2c396557fb87fa29efdf21060b868/bazel_cache/18545ad5d47fdc81034b726533d3cf62/execroot/_main_/src/mongo/db/modules/enterprise/src/streams/exec/window_aware_operator.cpp:706: FORWARD_NULL 171648 Dynamic cast to pointer "dynamic_cast <streams::SessionWindowAssigner *>(options.windowAssigner.get())" can return "NULL".
/data/mci/8df2c396557fb87fa29efdf21060b868/bazel_cache/18545ad5d47fdc81034b726533d3cf62/execroot/_main_/src/mongo/db/modules/enterprise/src/streams/exec/window_aware_operator.cpp:706: FORWARD_NULL 171648 Assigning: "assigner" = "dynamic_cast <streams::SessionWindowAssigner *>(options.windowAssigner.get())".