build: remove unnecssary check-prep target

[grondo]

This PR removes make check-prep in preference to the method @garlick used to build check prereqs in the macos build: make check TESTS=.

[chu11]

seems reasonable to me!

[grondo]

Hm , got an unrelated failure I haven't seen before:

 flux-broker: setattr tbon.endpoint: File exists
  flux-start: 1 (pid 486359) exited with rc=1
  flux-start: 1: PMI_Abort(): fatal bootstrap error
  test_must_fail_or_be_terminated: died by signal 13: flux start -Sbroker.rc1_path= -Sbroker.rc3_path= -s2 --setattr=tbon.endpoint=ipc:///tmp/customflux true
  not ok 18 - tbon.endpoint cannot be set

I'll restart that builder and keep an eye out for that failure in the future.

[grondo]

Thanks! I'll set MWP.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.43%. Comparing base (79cf207) to head (69c1691).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6550      +/-   ##
==========================================
- Coverage   83.74%   79.43%   -4.31%     
==========================================
  Files         531      531              
  Lines       88198    88185      -13     
==========================================
- Hits        73859    70054    -3805     
- Misses      14339    18131    +3792     

see 169 files with indirect coverage changes