Fix schema filter logic to prevent duplicated counts of tables

[kromiii]

When I tested the schema filter function with a Distance of 3 in a very small schema for the development, I noticed the following error often occurs in filter.go:

Failed to load schema: failed to filter schema: failed to separate tables. expected: 10, actual: 16

By checking the function, I found a bug in the aggregation logic of the filter function, which caused duplicate tables to be counted in includes2, so I had fix it.

[k1LoW]

@kromiii Thank you!