Latency histogram query in Function Explorer dashboard does not use build_info fallback

[brettimus]

In the functions explorer grafana dashboard, the query here uses the following to left-join the build_info metric:

# Attach the `version` and `commit` labels from the `build_info` metric
      * on (instance, job) group_left(version, commit) last_over_time(build_info[$__rate_interval])

Whereas the request and error ratio use

 * on(instance, job) group_left(version, commit) (last_over_time(build_info[$__rate_interval]) or on (instance, job) up)

When I execute the latency query as specified, and build_info has not yet been observed, then I get no data back

When I use the fallback or on (instance, job) up, I get data:

[brettimus]

i'll pick this up, seems like a simple fix