Add squid pkg to el8 and el9 images as user pkg

[aandvalenzuela]

Adding the package as requested in https://github.com/cms-sw/cms-docker/issues/235

[cmsbuild]

A new Pull Request was created by @aandvalenzuela (Andrea Valenzuela) for branch master.

@cmsbuild, @iarspider, @aandvalenzuela, @smuzaffar can you please review it and eventually sign? Thanks. @rappoccio, @antoniovilela, @sextonkennedy you are the release manager for this. cms-bot commands are listed here

[smuzaffar]

@aandvalenzuela , please make sure that it is available for all archs ( x86, aarch64 and ppc64le)

[aandvalenzuela]

They are! I could build the images locally in the three archs

[aandvalenzuela]

I am merging and triggering the tests