core/state/snapshot: soften log message when snapshot generation is paused

[fjl]

For #31184

[rjl493456442]

Abort is actually the right term here.

Snapshot generation occurs in multiple cycles and will be aborted
and restarted if the persistent state changes (the generation target
switches).

If the chain progresses, the process is aborted when a new state
layer is added on top, flooding users with excessive logs.

Fortunately, with #30661,
snapshot generation is now only aborted when the accumulated content
in the write buffer exceeds the threshold, significantly reducing the
frequency of interruptions.

[MariusVanDerWijden]

Maybe interrupting? I also think abort is a bit too strong