roachtest: add roachtest/workload for testing latency of ORM introspection queries

[rafiss]

We have rttanalysis tests for queries made by ORMs: https://github.com/cockroachdb/cockroach/blob/067dc92538d0d433218c588187263fc93b19985d/pkg/bench/rttanalysis/testdata/benchmark_expectations

But as #96218 shows, there still can be latency regressions even if round trips don't change. We got somewhat lucky in catching that regression.

If we had latency benchmarks, we would have caught that issue more easily.

cc @dikshant

Jira issue: CRDB-24085

[dikshant]

#102613 is another case that would be caught more easily if we had tests in place.

[dikshant]

Other cases are #93955 and #100871

[rafiss]

I will add this to the benchmark (from #102613)

SELECT
  current_database(), n.nspname, relname, d.description
FROM
  pg_description AS d
  INNER JOIN pg_class AS c ON d.objoid = c.oid
  INNER JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE
  d.objsubid = 0
  AND n.nspname
    NOT IN (
        'gp_toolkit':::STRING:::NAME,
        'information_schema':::STRING:::NAME,
        'pgagent':::STRING:::NAME
      )
  AND n.nspname NOT LIKE 'pg_%';

#93955 and #100871 are already being tested.

[rafiss]

Nevermind, that query is also there already:

cockroach/pkg/bench/rttanalysis/orm_queries_bench_test.go

Line 234 in de83c57

Stmt: `SELECT