folio-perf-test: Drop random, use deterministic records/search strings

We want folio-perf-test to run exactly the same queries each day.
Replace all random and all non-deterministic record/search string picking.

The setup picks 20 instances, 20 available items, 20 locations and 20 users (limit = number of threads):

Perf_Setup - GET inventory_instances?limit={limit}
Perf_Setup - GET inventory_items?query=(status.name=="Available")&limit={limit}
Perf_Setup - GET locations?limit={limit}
Perf_Setup - GET users?limit={limit}

This is not deterministic because there is not sort clause allowing the database to return any records.
One possibility is using limit={limit}&query=id==1234567* sortBy id (replace 1234567 by a suitable prefix that returns more than 20 records).

Several tests pick values for the query search string by random, for example "FOLIO-2154 search instance by contributors new array syntax" = "Perf - GET inventory/instances (contributors =/@name "{name}") sortby title":

    Random rand = new Random();
    ...
    def pick = rand.nextInt(size);
    def obj = resp.instances[pick].contributors;
    for (i = 0; i < obj.size(); i++) {
      def val = obj[i].name.trim();
      vars.put("contributorName", val);

For each test that uses Random come up with a hard-coded list. It should contain search strings with low and high hit count.