[aws|rds] Use correct filters in RDS model snapshots 'all' method

There is a bug in the implementation of the 'all' method in the RDS model 'snapshots' for AWS.

The error shows up if one passes arguments to the 'each' method. The 'all' method does not properly pick up the filters, which results in an infinite loop if more than one page of results exists.

The 'each' method sets the :marker key on self.filters but the previous implementation used the parameter passed to the method, not self.filters.