The testuser-experience rule: the suite must leave shared settings
exactly as it found them. setSystemSettingRestored snapshots the prior
system_settings row, writes through the sanctioned API path (the only
one that reloads the settings registry — raw SQL leaves the cache
stale), and registers a cleanup restoring what WAS there, never a
hardcoded value.
setExtractorVersion now rides it, so the ev-pin tests no longer
restore scan_extractor_version to a hardcoded 1: a deliberate dev bump
of the extractor version survives a suite run instead of being
silently cancelled (the live dev server obeys that setting on its next
poll and would stop re-extracting parser fixes). The now-redundant
explicit t.Cleanup restores are removed from
TestExtractorVersionReextract and pinExtractorVersionOne.