Improve rspec runtime info in job stack trace

What does this MR do and why?

This MR is the 2nd iteration for Print expected and actual spec duration in job log (!137931 - merged) with the following improvements:

1. changes from puts to Knapsack.logging.info so the expected run time data can be printed in the log. This was not working previously.
2. Change spec to use the output matcher everywhere in parallel_rspec_runner_spec.
3. prefix the runtime std output with # as suggested in !137931 (comment 1673879840)

Screenshots or screen recordings

# Example group Resolvers::Analytics::ContributionAnalytics::ContributionsResolver took 1.81 seconds.
# RSpec elapsed time: 38.91 seconds.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.