unordered_writes in local-config causes error

[TomRitserveldt]

Describe the bug
this PR: #4149 introduced the unordered_writes: true setting in the limits_config.
however, running loki 2.3.0, this throws an error on startup:

failed parsing config: loki-local-config.yaml: yaml: unmarshal errors:
  line 50: field unordered_writes not found in type validation.plain

To Reproduce
Steps to reproduce the behavior:

1. download and extract loki 2.3.0 on debian
2. download the latest loki-local-config.yaml from this repo
3. start loki with said config: ./loki-linux-amd64 -config.file=loki-local-config.yaml

Expected behavior
loki starts.

Environment:

• Infrastructure: debian buster VM
• Deployment tool: manual install.

Screenshots, Promtail config, or terminal output

# ./loki-linux-amd64 -config.file=loki-local-config.yaml
failed parsing config: loki-local-config.yaml: yaml: unmarshal errors:
  line 50: field unordered_writes not found in type validation.plain

[owen-d]

Thanks for your interest @TomRitserveldt! Unfortunately, that configuration is not available in 2.3, but will be in 2.4 when it's released :)