Disable Homebrew on Apple Silicon GitHub Actions CI runners

[ryandesign (Ryan Carsten Schmidt)]

source:macports-ports/.github/workflows/bootstrap.sh​ has code that disables the pre-installed Homebrew in /usr/local. But we now have the macOS 14 runner which is on Apple Silicon and on Apple Silicon Homebrew doesn't install in /usr/local; it installs in /opt/homebrew. We haven't disabled that. So Homebrew is still present for our macOS 14 CI builds and it is being used, for example in the run for ​this PR:

DEBUG: system: cd "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_textproc_po4a/po4a/work" && /usr/bin/gzip -dc '/opt/local/var/macports/distfiles/po4a/po4a-0.71.tar.gz' | /opt/homebrew/bin/gtar --no-same-owner -xf -

[ryandesign (Ryan Carsten Schmidt)]

And this problem has gotten baked into ​CI build of MacPorts for Darwin 23 so that will have to get recreated:

% grep /opt/homebrew -r opt 
opt/local/libexec/macports/lib/port1.0/port_autoconf.tcl:	variable lzma_path "/opt/homebrew/bin/lzma"
opt/local/libexec/macports/lib/port1.0/port_autoconf.tcl:	variable xz_path "/opt/homebrew/bin/xz"
opt/local/libexec/macports/lib/port1.0/port_autoconf.tcl:	variable git_path "/opt/homebrew/bin/git"
opt/local/libexec/macports/lib/port1.0/port_autoconf.tcl:	variable openssl_path "/opt/homebrew/bin/openssl"
opt/local/libexec/macports/lib/port1.0/port_autoconf.tcl:	variable tar_command "/opt/homebrew/bin/gtar --no-same-owner"
opt/local/libexec/macports/lib/macports1.0/macports_autoconf.tcl:    variable openssl_path "/opt/homebrew/bin/openssl"
opt/local/libexec/macports/lib/macports1.0/macports_autoconf.tcl:    variable tar_command "/opt/homebrew/bin/gtar --no-same-owner"

[ryandesign (Ryan Carsten Schmidt)]

I guess that's not due to bootstrap.sh; it's a separate problem to be fixed in source:macports-base/.github/workflows/main.yml​

[ryandesign (Ryan Carsten Schmidt)]

I'm not sure why the macports-base and macports-ports workflows use two different strategies for disabling Homebrew. Seems like there should be a single script to do that that can be called from both places.

Or, why does the macports-base workflow need to disable Homebrew at all? We already know that we should set PATH=/usr/bin:/bin:/usr/sbin:/sbin before running ./configure to avoid pulling in dependencies from an already-installed MacPorts. If we had done that, we would have avoided pulling in dependencies from Homebrew and anywhere else too.

[jmroot (Joshua Root)]

In 55d389d538d03e817bbed26f37d6de821ae0cbde/macports-base (master):

CI: Control configure environment

See: #69661

[jmroot (Joshua Root)]

In 59d996af4241a24e5e78cb218bc5602a1ea44894/macports-ports (master):

CI: also remove /opt/homebrew

Closes: #69661