make flux resource drain -o long reason expandable

[garlick]

Problem: the "long" format of 'flux resource drain' doesn't show the un-truncated drain reason, but one might expect that to be the case.

Now that we have expandable field width support, use it for {reason} in the "long" format. In addition, to conserve space, {timestamp} is changed to use same format as "default", since the longer representation wasn't particularly helpful.

$ flux resource drain
TIME         STATE    REASON                         NODELIST
Oct02 13:06  drained  This is a long drain message + pop-os
$ flux resource drain -o long
TIME         STATE    RANKS    REASON                                NODELIST
Oct02 13:06  drained  0        This is a long drain message isnt it? pop-os

Same for {reason} in the "long" format of 'flux resource status':

$ flux resource status -o long
       STATE UP NNODES REASON                                NODELIST
     drained  ✔      1 This is a long drain message isnt it? pop-os

[wihobbs]

Ahh thanks I was just looking for this the other day!

[grondo]

Nice improvement! 👍

[garlick]

Thanks! Setting MWP.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.33%. Comparing base (367243a) to head (e5f695e).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6338      +/-   ##
==========================================
- Coverage   83.34%   83.33%   -0.02%     
==========================================
  Files         523      523              
  Lines       86183    86183              
==========================================
- Hits        71833    71819      -14     
- Misses      14350    14364      +14     

Files with missing lines	Coverage Δ
src/cmd/flux-resource.py	94.97% <ø> (ø)

... and 8 files with indirect coverage changes