CI: update nightly builds to use universal mac update

[onetechnical]

Summary

In #6023 we added a universal mac build target. We should switch to this as it's a simplified model for handling Mac binaries. This PR takes the first step by migrating our nightly builds to use this by default.

Note that I did not want to just make Mac universal builds the default for make build. It does, however, presume if you run make universal that you want that as your primary binary.

Also removed arm32 from the updater script, as that platform support has been deprecated.

Test Plan

Been running steps individually, but will also need to see if nightly build/promotion works.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 56.11%. Comparing base (48a539f) to head (ebb1b5c).
Report is 5 commits behind head on master.

Files	Patch %	Lines
util/s3/s3Helper.go	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6071      +/-   ##
==========================================
- Coverage   56.13%   56.11%   -0.02%     
==========================================
  Files         488      488              
  Lines       69439    69445       +6     
==========================================
- Hits        38978    38968      -10     
- Misses      27813    27823      +10     
- Partials     2648     2654       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[algorandskiy]

LGTM, one remark about naked return stmt.