Loki doesn't create _extracted label suffix if there is more than one parser

[KimMJ]

Describe the bug
If the log has multiple depths and overlapping labels are encountered by a later parser, they will be ignored instead of creating labels with the _extracted suffix.

To Reproduce
Steps to reproduce the behavior:

1. Loki version 2.9.4
2. Log message:

   {"destination":"common","filepath":"/logs/envoy/current.log", "level":"INFO","log":"2024-04-26T08:52:04.746547Z\twarn\tEOF","timestamp":"2024-04-26T08:52:05.450Z"}
   

3. Query: {<stream_selector>} | json | line_format "{{.log}}" | pattern "<time>\t<level>\t<message>"

Expected behavior

I exptected to see level=warn label kv, but it wasn't and there is no level_extracted label neither

Environment:

• Infrastructure: Kubernetes (EKS 1.28)
• Deployment tool: jsonnet
• Version: 2.9.4

[timansky]

Same bug with 3.0.0 version and level field in json

Infrastructure: Kubernetes (vanila 1.28)
Deployment tool: manual
Version: 3.0.0