fixed assertion error in ShardedDOMDataWriteTransactionTest

fixed assertion error in ShardedDOMDataWriteTransactionTest

getIdentifier() method returns String (as a name) and counter in form
of incremented Atomic long in every new instantiation. Before this
change test exactly expected to have an 0 and then 1 at counter side,
but if some other test create an instance of
ShardedDOMDataWriteTransaction before this test, counter will alredy be
greater than 0 so presumably that is what happend and test is order
dependant. I removed this dependency and now test is checking for
non-equality of two differend object identifiers, so does not matter
what is at counter side at beggining of this test.

Change-Id: I65401ea99bc7d8d94e4ef1fc9b52a1b9909f63fe
Signed-off-by: Peter Nosal <peter.nosal@pantheon.tech>