ec.encode: name the shard ids an aborted deletion found (#10486)

Counting by node lost the per-node ShardsInfo, and with it the shard ids the
old summary printed -- the message an operator gets when the pre-delete check
refuses now says only how many shards each node holds.

That is the wrong half. A set holding shards 0-9 and one holding 4-13 are
both "10 shards", and only the ids say whether what survived can rebuild the
volume, or which node to go looking at. Keep the count and list the ids
beside it.

weed/shell/command_ec_encode_test.go

@@ -466,3 +466,19 @@ func TestEcShardCountIgnoresDiskTypeOfTheShards(t *testing.T) {
 	scoped, _ := collectEcNodeShardsInfo(topo, needle.VolumeId(1), types.ToDiskType(""))
 	assert.Empty(t, scoped, "the hdd-scoped view cannot see ssd shards")
 }
+
+// The message an aborted deletion leaves behind is all the operator has to go
+// on, so it has to name which shards were found and not only how many: a set
+// holding 0-9 and one holding 4-13 are both "10 shards", and only the ids say
+// whether what survived can rebuild the volume.
+func TestEcShardSummaryNamesTheShardIds(t *testing.T) {
+	byNode := map[pb.ServerAddress]erasure_coding.ShardBits{
+		"node2:8080": erasure_coding.ShardBits(0).Set(1).Set(2),
+		"node1:8080": erasure_coding.ShardBits(0).Set(0).Set(12),
+	}
+
+	assert.Equal(t, []string{
+		"node1:8080=2 shards [0 12]",
+		"node2:8080=2 shards [1 2]",
+	}, ecShardSummaryByNode(byNode))
+}