When we call run_when_memory_available, it is entirely possible that
the caller is doing that inside a scheduling_group. If we don't defer
we will execute correctly. But if we do defer, the current code will
execute - in the future - with the default scheduling group.
This patch fixes that by capturing the caller scheduling group and
making sure the function is executed later using it.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
3b53f922a3