What did you do?

Expose an a metric with exemplar from client_go (via opentelemetry), where one of the labels features a non-traditional character in the label (e.g. http.scheme),

What did you expect to see?

This is exported in sccraping as:

metric_total{n="1"} 0 # {"net.http"="abc"} 1.0

Prometheus then fails to scrape this due to the presence of the quote:

 expected label name, got "\"" ("INVALID") while parsing: "metric_total{n=\"1\"} 0 # {\""

What did you see instead? Under which circumstances?

Prometheus should successfully scrape the quote label name.

System information

Linux 6.11.5-arch1-1 x86_64

Prometheus version

tested on 
commit: dd4eb4590dc7f4163afb452fd3f2f189caf2d20f

discovered via opentelemetry collector using 

github.com/prometheus/prometheus v0.54.1

### Prometheus configuration file

_No response_

### Alertmanager version

_No response_

### Alertmanager configuration file

_No response_

### Logs

_No response_