macOS: A newer pkg file can not install over an older version

This issue is to investigate if there can be an improvement to the macOS installer as several reports have been raised over not being able to install over top of an older version.

Comments from https://github.com/adoptium/temurin-build/issues/4549#issuecomment-5418108003 and https://github.com/adoptium/temurin/issues/298#issuecomment-5344278080 indicate the issue.

> I found the issue: I had an “old” Temurin 25.0.4+7 installed, downloaded the new .pkg file and installed it. Everything looks OK, but the release file was still the old and java -version showed the old 25.0.4+7 LTS.

> I zapped the temurin-25-jdk directory under /Library/Java/… then installed silently and this worked fine. So it’s a .pkg issue somehow. Your distribution is OK, just that .pkg cannot install over another older version apparently.

Start by reproducing installation with an older Temurin version present, using the referenced reports as the expected failure scenario. Inspect the macOS .pkg installation behavior around /Library/Java/... and compare normal and silent installs. Done means a newer package replaces the older installation and java -version reports the newer release.

Written by the indexing model from the issue text.