Previously such expressions were improperly formatted, which could result
in incorrect calculations at vlogscli.
For example, 'x / (y / z)' was formatted as 'x / y / z',
while 'x - (y + z)' was formatted as 'x - y + z'.
(cherry picked from commit 80c5066ef3)
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.
