qmanager: track API changes in core

[garlick]

Problem: the raw RPC interfaces are changing to use a size_t instead of int for payload size.

Update scheduler usage.

flux-framework/flux-core#6467 must be merged before this will pass CI.

[grondo]

LGTM

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.5%. Comparing base (6a7ecc0) to head (139d021).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #1320      +/-   ##
=========================================
+ Coverage    75.2%   82.5%    +7.3%     
=========================================
  Files         111      32      -79     
  Lines       15986    4183   -11803     
=========================================
- Hits        12029    3455    -8574     
+ Misses       3957     728    -3229     

see 85 files with indirect coverage changes