Main changes:

1) DruidSqlValidator now includes a rewrite of IN to SCALAR_IN_ARRAY, when the size of
   the IN is above inFunctionThreshold. The default value of inFunctionThreshold
   is 100. Users can restore the prior behavior by setting it to Integer.MAX_VALUE.

2) SearchOperatorConversion now generates SCALAR_IN_ARRAY when converting to a regular
   expression, when the size of the SEARCH is above inFunctionExprThreshold. The default
   value of inFunctionExprThreshold is 2. Users can restore the prior behavior by setting
   it to Integer.MAX_VALUE.

3) ReverseLookupRule generates SCALAR_IN_ARRAY if the set of reverse-looked-up values is
   greater than inFunctionThreshold.

Co-authored-by: Benedict Jin <asdf2014@apache.org>