Add parameter to limit the size of a query string

[kamalesh0406]

Description

I added the parameter to limit the size of the query string in a user input. Further, I moved validate_request out of the for loop since many of the checks inside it did not require to be run for each index_metadata.

An alternate approach for checking the query size could be to match the enums in the serialized query_ast value and check the size of the actual user input.

How was this PR tested?

New unit tests to check if the error is thrown.