Since this script just runs vacuumdb anyway, remove the script and
replace the instructions to run it with instructions to run vacuumdb
directly.

Reviewed-By: Michael Paquier
Discussion: https://postgr.es/m/CABUevEwg5LDFzthhxzSj7sZGMiVsZe0VVNbzzwTQOHJ=rN7+5A@mail.gmail.com