versions_scanned for both the scanner and ILM collectors was read from
the Lifecycle work source's `checked` counter, which is never recorded on
the production scan path — so rustfs_scanner_versions_scanned_total and
rustfs_ilm_versions_scanned_total sat at zero even while objects_scanned
climbed. The two metrics also have distinct intended meanings that were
conflated: "versions scanned" (all versions, any bucket) vs "versions
checked for ILM actions" (lifecycle-configured buckets only).
Add a lifetime `versions_scanned` counter recorded for every version the
scanner walks (independent of ILM), and record the Lifecycle source's
`checked` counter from the ILM evaluator so the ILM metric reflects the
real checked subset. The scanner collector now reports total scanned
versions; the ILM collector keeps the ILM-checked subset.
Closes backlog#995 (OBS-09).
Co-authored-by: heihutu <[email protected]>
