Exclude tables from snapshot: handle C*2.1 naming

[rhardouin]

As you can see, C*2.0 compatibility is kept:

C*2.1

>>> table_name_with_uuid = 'mytable-15165f11e3f634af9d3afacf98868599'
>>> table_name = table_name_with_uuid.split('-')[0]
>>> table_name
'mytable'

C*2.0

>>> table_name_with_uuid = 'mytable'
>>> table_name = table_name_with_uuid.split('-')[0]
>>> table_name
'mytable'