Unconditionally upgrade installed Brew packages on OSX

[directhex]

With Apt, if you have X 1.0 installed, 1.1 exists in the package manifest, and say "install X", X is upgraded to 1.1. With Brew, a fatal error is thrown.

Blindly upgrading all previously installed packages is not ideal, and not a perfect mirror for the Apt behaviour, but it should mean that if X is previously installed it gets upgraded (causing a warning during install, when it's asked to be installed again with the same version), and if it's not already installed then it gets installed later.

Closes: #33471

[jashook]

Won't this update our native toolsets unconditionally?

[directhex]

@jashook yup. But by calling brew update, as is already the case, the cache of available versions is already "latest at time of build", so either we need to pin specific versions in install-native-dependencies.sh (i think brew supports this?), or find some other mechanism to conditionally upgrade some specific packages.

As is, updating the package manifest to latest and asking "install the latest version of these 7 packages" will always cause failures when any one of those 7 is updated, as is the case today.

Brew is not smart.

[jaredpar]

Is there a way to limit the brew upgrade to just python? Looking through the log that seems to be the only source of our failures right now.

Either way we should proceed with some version of this as a stop gap measure. Builds are failing 100% right now (just verified). This will at least get us unblocked until we can find the appropriate longer term fix.

[jashook]

Also seems to me if these machines already have a python3 installed (which seems to have changed) we just should not brew install python3

[jashook]

I was suggest a small check if python3 does not exists then brew install python

[directhex]

@jaredpar brew upgrade X if X is not installed is a failure, and brew install X if X is already installed but not $latest is a failure. Not installing python3 seems like it means we can't bootstrap new machines at all with install-native-dependencies.sh. Brew simply lacks a command for either install this set of packages but don't upgrade them or install this set of packages and upgrade any in this set which are out of date.

[directhex]

We can put in a python specific conditional, as long as we're certain that there will never be an issue released for icu4c, openssl, autoconf, automake, libtool, or pkg-config where we're gonna end up in this exact situation again.

[jashook]

They would have to be present on the vm provided to us by azdo to have the conflict. Python3 seems understandable why they would add that, the rest may or may not be added. However, personally I find conditionally checking python3 and hoping the other packages are not added a safer solution. Seeing that this is also used by our official build (see below).

[jashook]

However, on further thought, we already always install the latest package anyways. So I think I am fine with either solution.

[jashook]

Merging to unblock the ci.

[jashook]

@directhex thank you for the quick fix