The is_joined() status can be get with get_operation_mode(). Since
it indicates that the operation mode is JOINING, NORMAL or anything
above, the operation mode the enum class should be shuffled to get
the simple >= comparison.
Another needed change is to set mode few steps earlier than it
happens now to cover the non-bootstrap startup case.
And the third change is to partially revert the d49aa7ab that made
the .is_joined() method be future-less. Nowadays the is_joined() is
called only from the API which is happy with being future-full in
all other storage service state checks.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
ffbfa3b542