Prettify functionality for the binary operations adds additional braces

[dmitryk-dk]

If you try to prettify the query

(1 - (node_memory_MemFree_bytes + node_memory_Cached_bytes + node_memory_Buffers_bytes + node_memory_SReclaimable_bytes) / node_memory_MemTotal_bytes) * 100

You will get the result:

(
  1
    -
  (
    (
      (
        (node_memory_MemFree_bytes + node_memory_Cached_bytes)
          +
        node_memory_Buffers_bytes
      )
        +
      node_memory_SReclaimable_bytes
    )
      /
    node_memory_MemTotal_bytes
  )
)
  *
100

It happens because braces are always add if it is BinaryOpExpr
https://github.com/VictoriaMetrics/metricsql/blob/master/parser.go#L1935
and
https://github.com/VictoriaMetrics/metricsql/blob/master/parser.go#L1980