[BUG] bug in label encoding of `exp_store`

[BingqingLyu]

Describe the bug

Run the following query with exp_store on LDBC dataset outputs empty results, which is not as expected: g.V().has("COUNTRY", "name", "India").in("ISPARTOF").hasLabel("CITY")

This is caused by the hierarchical label structure (two-layers) in exp_store. For example, a "PERSON" would be encoded as [PERSON, INVALID_LABEL_ID], while a "CITY" whould be encoded as [PLACE, CITY]. However, we only take the firstly layer of label for now. e.g., when compared with CITY, we take label of PLACE, which leads to the wrong answer.

[longbinlai]

I've tested using local exp_store. The results are not empty.