install_prerequisites.py: proper handling of curl on EL9+

[SwooshyCueb]

At present, for EL9, we remove curl from the list of packages to install, with a comment explaining the rationale:

externals/install_prerequisites.py

Lines 146 to 149 in 1b220bc

	if int(distro_major_version) == 9:
	# For version 9, curl is installed by another step of this process and manually installing the package
	# here creates a conflict. Just delete curl from the list of packages to install.
	main_package_list.remove('curl')

However, this comment doesn't tell the whole story.
Starting with EL9, by default, curl and libcurl are provided by curl-minimal and libcurl-minimal, respectively. The way this was accomplished was a bit janky, as the package manager will not always automatically evict the -minimal packages when someone is trying to install the full variants.
the -minimal packages are suitable for our purposes, so the proper solution here is to install curl-minimal on EL9+.