fix quantile_exact parameter error

[lizhou1111]

PR checklist:

• Did you run ClangFormat ?
• Did you separate headers to a different section in existing community code base ?
• Did you surround proton: starts/ends for new code in existing community code base ?

Please write user-readable short description of the changes:

[lizhou1111]

this close #725

[yokofly]

add a test? either in stateless or in smoke.