filer: an unrepresentable remaining TTL means no volume TTL

The fallback capped the remainder at MaxInt32 seconds, which the volume
TTL grid encodes as 68 years - about 35 days shorter than the entry's
lifetime. For the narrow band nothing can round up within int32, store
the chunks without a volume TTL instead: they outlive the entry rather
than predecease it.

weed/server/filer_server_format.go

@@ -65,7 +65,9 @@ func roundUpToVolumeTTL(seconds int64) int32 {
 			return int32(count * unit)
 		}
 	}
-	return math.MaxInt32
+	// Nothing above ~68 years rounds up within int32; no volume TTL keeps the
+	// chunks past the entry, which is the safe direction.
+	return 0
 }
 
 // formatChunkSizeLimit mirrors the autoChunk maxMB resolution.