Re: Optimize JsonbContainerTypeName by reordering type checks

Hi Hacker,

This is an innocent refactor that doesn't change logic and improve
performance of jsonb_typeof() a little bit.

I have done a performance test that proves a tiny performance improvement:

With the master branch:
```
% pgbench -n --no-vacuum -T 120 -c 8 -j 4 -f test_jsonb_type.sql evantest
tps = 83290.213196 (without initial connection time)

# second run
tps = 83709.266846 (without initial connection time)

# third run
tps = 83531.014990 (without initial connection time)
```

With this patch:
```
% pgbench -n --no-vacuum -T 120 -c 8 -j 4 -f test_jsonb_type.sql evantest
tps = 84172.324715 (without initial connection time)

# second run
tps = 84082.619469 (without initial connection time)

# third run
tps = 84260.671778 (without initial connection time)
```

With 3 runs average tps, this patch makes ~0.8% improvement for
jsonb_typeof().

My test script is attached, it can run against any database. And attached
v2 patch file has a tiny change over v1.

Best regards,
Chao Li (Evan)
---------------------
HighGo Software Co., Ltd.
https://www.highgo.com/