SearchV2 merger does not preserve meta DB ordering for some system attributes

[cthulhu-rider]

meta DB stores and cmps following attributes as plain bytes:

• owner
• payload SHA-256
• payload TZ
• split ID
• all OIDs (first and parent)

on match, they go to the result in protocol string fmt. On merge multiple results from several sources (shards, nodes), merge func cmps them lexicographically. If string fmt does not preserve byte order, the order can break on merge

Expected Behavior

keep order returned from the meta DBs

Current Behavior

the order can break

Possible Solution

1. check which ones are problematic. Being base58btc strings, owner and OIDs are definitely are. Check the others
2. fix cmp in the merge func

Context

• Implement searchv2 #3058

[cthulhu-rider]

payload SHA-256 and TZ hashes are HEX strings, so the order is preserved

ive got following results for others

func checkOrder[T fmt.Stringer](name string, rnd func() T, cmp func(a, b T) int) {
	s := make([]T, 1000000)
	for i := range s {
		s[i] = rnd()
	}
	slices.SortFunc(s, cmp)
	ss := make([]string, len(s))
	for i := range s {
		ss[i] = s[i].String()
	}
	fmt.Println(name, "order kept:", slices.IsSorted(ss))
}

func TestOrder(t *testing.T) {
	checkOrder("OID", oidtest.ID, func(a, b oid.ID) int { return bytes.Compare(a[:], b[:]) })
	checkOrder("User", usertest.ID, func(a, b user.ID) int { return bytes.Compare(a[:], b[:]) })
	checkOrder("UUID", uuid.New, func(a, b uuid.UUID) int { return bytes.Compare(a[:], b[:]) })
}

UUIDs (split ID) are HEX-encoded, too, so OK. OIDs are expectedly broken

the one that surprises me a bit is user ID: it's base58btc-encoded as well as OID, but order is kept. Mb the fact that it has fixed prefix affect smth, but i wouldnt rely on this for now. At the same time, in practice I couldnt find two user IDs with disorder