This eliminates possible bugs related to forgotten Query.Optimize() calls.
This also allows removing optimize() function from pipe interface.
While at it, drop filterNoop inside filterAnd.
This is needed for avoiding confusion between the `|` operator at `math` pipe and `|` pipe delimiter.
For example, the following query was parsed unexpectedly:
* | math foo / bar | fields x
as
* | math foo / (bar | fields) as x
Substituting `|` with `or` inside `math` pipe fixes this ambiguity.
