influxdb shows measurement with random garbage name

__Steps to reproduce:__
List the minimal actions needed to reproduce the behavior.

1. show measurements
2. ...
3. ...

__Expected behavior:__
all measurements should be human readable

__Actual behavior:__
seen one measurement which has garbage values
```
> show field keys from /.*I.*/
name: ����?I[O��QJ3�:���E��Qv��:L�Q
fieldKey fieldType
-------- ---------
�v+'����:�R�����hwʉ-��bRXOVҊ�p�f:YC[���Q2T���
�F �c���Γg� string
> show tag keys from /.*I.*/
```

__Environment info:__

* System info: Run `uname -srm` and copy the output here
```
Linux 5.4.0-1036-gcp x86_64
```
* InfluxDB version: Run `influxd version` and copy the output here
```
# influxd version
InfluxDB v1.8.4 (git: 1.8 bc8ec4384eed25436d31045f974bf39f3310fa3c)
```
* Other relevant environment details: Container runtime, disk info, etc

__Config:__
Copy any non-default config values here or attach the full config as a gist or file.

__Logs:__
Include snippet of errors in log.

__Performance:__
Generate profiles with the following commands for bugs related to performance, locking, out of memory (OOM), etc.

```sh
# Commands should be run when the bug is actively happening.
# Note: This command will run for ~30 seconds.
curl -o profiles.tar.gz "http://localhost:8086/debug/pprof/all?cpu=30s"
iostat -xd 1 30 > iostat.txt
# Attach the `profiles.tar.gz` and `iostat.txt` output files.
```

Start by reproducing the listed `show measurements`, `show field keys from /.*I.*/`, and `show tag keys from /.*I.*/` commands against InfluxDB v1.8.4 on Linux. Read the surrounding database and query behavior after confirming the garbage measurement; done means the same data no longer produces an unreadable measurement name and the behavior is covered by a reproducible check.

Written by the indexing model from the issue text.