Increase time upper time buckets in histograms

[masih]

Increase the time upper bound time buckets for histogram metrics that measure:

• committee fetch time
• proposal fetch time
• validation time per message

Fixes #780

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.32%. Comparing base (0a6bda4) to head (64a1a70).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #781      +/-   ##
==========================================
- Coverage   69.36%   69.32%   -0.04%     
==========================================
  Files          76       76              
  Lines        7870     7870              
==========================================
- Hits         5459     5456       -3     
- Misses       1959     1961       +2     
- Partials      452      453       +1     

Files with missing lines	Coverage Δ
metrics.go	82.50% <ø> (ø)

... and 3 files with indirect coverage changes