Opprotunistically prune run condition spans

[james7132]

What problem does this solve or what need does it fill?

A span for profiling has non-insignificant overhead (#4892) and a good chunk of run conditions don't take very long to run. The construction of these spans is a few orders of magnitude greater than the time it takes to run the condition itself. This is skewing profiling measurements of the executor when there are a lot of these conditions.

What solution would you like?

Opportunistically avoid making these spans when we know that the time spent in the condition is low.

What alternative(s) have you considered?

1. Leave it be. Accept the overhead and factor it into our evaluations of performance changes.
2. Omit them entirely.
3. Put them behind a feature flag.