This commit has two related changes:

1. Clean up and document recent changes in the benchmark script. One of
   these changes is replacing ad-hoc rewrites of `package.json` files
   with a firm reliance on the `publishConfig` field, which should be
   reliable (since that's what we use when actually publishing).
2. Update all of the `package.json` files for published packages to have
   consistent `publishConfig` fields. This change also removed a bunch
   of historical cruft from the `package.json` files, which helped us
   to support environments during the ecosystem transition to
   package.json `exports` fields.