MOVEFILE_DELAY_UNTIL_REBOOT was the quarantine's last resort, and it is worse
than doing nothing. It writes to HKLM, so a non-elevated update — every
Desktop-driven one, and most terminal ones — gets ERROR_ACCESS_DENIED and
reports nothing. When it does succeed it frees nothing for the install
running right now, and the queued operation outlives that update: at the next
boot it moves aside whatever sits at the shim path, including a shim a later
repair just wrote.
Drops the fallback and sweeps entries older versions queued, matching only
our own <shim> -> <shim>.old.<stamp> pairs so unrelated installers keep
theirs.
Salvaged from #88121 by @fangliquanflq.
a9eb99d172