[physical][postgresql] `concat`→`||` operator (#2945)
[physical][postgresql] `concat`→`||` operator (#2945)

Use `||` standard concatenation instead of the `concat` function in
order to use the `vault_kv_store` index on `parent_path`.
naunga/vault,mgk/vault,quixoten/vault,hashicorp/vault,rnaveiras/vault,quixoten/vault,joelthompson/vault,tallpauley/vault,mgk/vault,quixoten/vault,mgk/vault,deverton/hashicorp-vault,lemondrank/vault,hartsock/vault,kingland/vault,Aloomaio/vault,kingland/vault,hashicorp/vault,naunga/vault,Aloomaio/vault,rnaveiras/vault,wjam/vault,hartsock/vault,lemondrank/vault,Caiyeon/vault,deverton/hashicorp-vault,Caiyeon/vault,rnaveiras/vault,rnaveiras/vault,rnaveiras/vault,quixoten/vault,hashicorp/vault,lirao/vault,hartsock/vault,hartsock/vault,Aloomaio/vault,joelthompson/vault,Aloomaio/vault,mgk/vault,joelthompson/vault,hartsock/vault,lirao/vault,hashicorp/vault,kingland/vault,hashicorp/vault,kingland/vault,tallpauley/vault,hashicorp/vault,kingland/vault,joelthompson/vault,wjam/vault