gh-101981: Update macOS workflow

[corona10]

• Issue: CI: intermittent macOS failures for make checksharedmods #101981

[ned-deily]

Why not follow the devguide recipe and use one shell line? Those variables should only be needed for the configure command

[corona10]

@ned-deily

• multi line string needs to declare sperate variable for this: https://trstringer.com/github-actions-multiline-strings/
  So we use single line command most of cases.

[ned-deily]

• multi line string needs to declare sperate variable for this: https://trstringer.com/github-actions-multiline-strings/

But the devguide recipe does not consist of multiple commands on multiple lines as in that link, i.e. it's not "in the form of an output from one step, and an input to another step". It's a single shell command that has been split across lines in the devguide for readability and it doesn't need to be. (The POSIX command language standard calls it a "simple command": "A simple command is a sequence of optional variable assignments and redirections, in any sequence, optionally followed by words and redirections, terminated by a control operator." There is no piping involved here.)

[bedevere-bot]

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

[corona10]

I have made the requested changes; please review again

I am thinking about how to resolve test_freeze_simple_script

[corona10]

I have made the requested changes; please review again

[bedevere-bot]

Thanks for making the requested changes!

@ned-deily: please review the changes made to this pull request.