db: set hideObsoletePoints for "boomerang" files

We weren't setting this flag correctly When a shared file is ingested
by another store and then ingested back into the original store,
leading to an "out of order keys" error in `TestMetaTwoInstances`.

Informs #3174.

table_cache.go

@@ -545,10 +545,11 @@ func (c *tableCacheShard) newIters(
 		rp = &tableCacheShardReaderProvider{c: c, file: file, dbOpts: dbOpts}
 	}
 
-	if provider.IsSharedForeign(objMeta) {
+	if objMeta.IsShared() && v.reader.Properties.GlobalSeqNum != 0 {
 		if tableFormat < sstable.TableFormatPebblev4 {
-			return nil, nil, errors.New("pebble: shared foreign sstable has a lower table format than expected")
+			return nil, nil, errors.New("pebble: shared ingested sstable has a lower table format than expected")
 		}
+		// The table is shared and ingested.
 		hideObsoletePoints = true
 	}
 	var categoryAndQoS sstable.CategoryAndQoS