rust: remove excessive calls to `#[timed]`
This makes trace output *really* noisy and is only useful in case you want to
take a look at a single revlog.
This is easy to add back on a case-by-case basis and does not need to stay with
the more permanent timers.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}