mark all ranks known to graph when "all" is specified

[trws]

This changes the behavior a bit, in that it marks all ranks known to the database. The original tried to mark all ranks active in flux, but marked the first N. The new behavior seems more intuitive, but we may want to change it if we grow or shrink in the future.

fixes #1040

[codecov]

Codecov Report

Merging #1042 (bd426cd) into master (32f74d6) will increase coverage by 0.0%.
The diff coverage is 100.0%.

❗ Current head bd426cd differs from pull request most recent head ac204c2. Consider uploading reports for the commit ac204c2 to get more accurate results

@@          Coverage Diff           @@
##           master   #1042   +/-   ##
======================================
  Coverage    74.4%   74.4%           
======================================
  Files          86      86           
  Lines        9434    9432    -2     
======================================
- Hits         7021    7020    -1     
+ Misses       2413    2412    -1     

Impacted Files	Coverage Δ
resource/modules/resource_match.cpp	72.1% <100.0%> (+<0.1%)	⬆️

[grondo]

Tested this and it is working as expected, thanks!