Fail queries that have two aggregations with the same name.

Close #6255
[TEST] Added test for #6256
[TEST] prevent dummy documents from being indexed in testSimpleQueryString() since scores are compared
Fix FieldDataWeighter generics to accept RamUsage instead of AtomicFieldData

The `FieldDataWeighter` allowed to use a concrete subclass of the caches
generic type to be used that causes ClassCastException and also trips the
CirciutBreaker to not be decremented appropriately.

This was tripped by settings randomization also part of this commit.

Closes #6260
Percolator: Fix assertion in percolation with nested docs

Assertion was triggered for percolating documents with nested object
in mapping if the document did not actually contain a nested object.
Reason:
MultiDocumentPercolatorIndex checks if the number of documents is
actualu >1. Instead we can just use the SingleDocumentPercolatorIndex
in this case.

closes #6263
More Like This Query: replaced 'exclude' with 'include' to avoid double negation when set.

Closes #6248