Remove Leap15.1 profiles

[phillxnet]

As we near our Rockstor 4 re-launch, which is specified as 'Built on openSUSE Leap 15.2' and given our move to multi arch, the recent inclusion of a couple of aarch64 targets (Pi4 & ARM64EFI), it is proposed that we remove the Leap 15.1 profiles. This proposal is in the light of Leap 15.0 & 15.1 having served as our run-up to the Rockstor 4 release on a 15.2 base, and the fact that in 2 months time, from this issues creation, Leap 15.1 is EOL: see https://en.opensuse.org/Lifetime (November 2020).

The additional repo base target is also a significant draw on our limited resources and ends up thinning out our available testing resources, both computational and human. We are now also looking to the jump directive that aims to further the binary compatibility and kinship of openSUSE Leap and SLES offerings. This is a far more important target to concern ourselves with in the future than the soon to be EOL Leap 15.1 from our development past. And given Jump 15.2 now has an alpha release we should look to pruning our prior development targets to make way for the new development target of Jump 15.2 and in turn it's successor.

This removal of the Leap 15.1 base should also help to avoid the 'optic' that we will be supporting a Leap 15.1 Rockstor 4 base as this is not the case. It was a development stepping stone, as was 15.0 before it, to the more appropriate Leap 15.2 that we have indicated as our preferred Rockstor 4 re-launch base.

[phillxnet]

Adding references for the Jump initiative:
https://en.opensuse.org/Portal:Jump
https://en.opensuse.org/Portal:Leap/FAQ/ClosingTheLeapGap
https://progress.opensuse.org/projects/jump_152/issues
https://en.opensuse.org/Portal:Jump/Kernel

[phillxnet]

Leap 15.1 is now EoL (extended from original issue text) as from Feb 2nd 2021.

Given our pending addition of Leap 15.3 profiles:

"Add Leap 15.3 profile for x86_64 & Aarch64" #46

and our delayed Stable release via the 'Built on openSUSE' Leap 15.2 initiative we should now clear the way for this new OS base by tending to this house-keeping issue. Those in need, post this issue resolution, can always checkout an older version of this repo.

[phillxnet]

I am currently working on this issue.