SELECT * from /.*/ does not select string values

More precisely, it seems matching measurement name by regex returns string fields only if no other measurement with numerical fields also match.

I believe this is the root cause for #18132.

Steps to reproduce:

> create database playground
> use playground
Using database playground
> insert temperature,sensor=foo value=17.2
> insert temperature,sensor=foo value=14.6
> insert state,sensor=foo value="pending"
> insert state,sensor=foo value="complete"
> SELECT * from /.*/

Expected behavior:

name: temperature
time                sensor value
----                ------ -----
1608201930629827407 foo    17.2
1608201942532968798 foo    14.6
name: state
time                sensor value
----                ------ -----
1608201948581612466 foo    pending
1608201954413360691 foo    complete

Actual behavior:

Only temperature selected

name: temperature
time                sensor value
----                ------ -----
1608201930629827407 foo    17.2
1608201942532968798 foo    14.6

Note that state can be selected without regex:

> SELECT * from state
name: state
time                sensor value
----                ------ -----
1608201948581612466 foo    pending
1608201954413360691 foo    complete

or if it is the only match:

> SELECT * from /ate/
name: state
time                sensor value
----                ------ -----
1608201948581612466 foo    pending
1608201954413360691 foo    complete

but not if temperature matches too:

> SELECT * from /te/
name: temperature
time                sensor value
----                ------ -----
1608201930629827407 foo    17.2
1608201942532968798 foo    14.6

Looks like there's something fishy going on. This looks more like a bug than an intended behaviour.

Environment info:

• System info: Linux 4.19.0-13-cloud-amd64 x86_64
• InfluxDB version: InfluxDB v1.8.3 (git: 1.8 563e6c3d1a7a2790763c6289501095dbec19244e)
• Other relevant environment details: Container runtime, disk info, etc

Reproduce the issue using the provided database, measurement, and SELECT commands, then trace regex measurement selection and field handling. Done means SELECT * from /.*/ returns both temperature and state, including the string values, with a regression test covering the mixed numeric and string measurements.