data-vis-sdk: make llvm~libomptarget the default (#40007)

Currently the configuration of the pipeline is such that
there are multiple "optimal" solutions. This is due to
the pipeline making ~lld the default for LLVM, but leaving
+libomptarget from package.py

Since LLVM recipe has a:

conflicts("~lld", "+libomptarget")

clingo is forced to change one of the two defaults, and
the penalty for doing so is the same for each. Hence, it
is random whether we'll get +libomptarget+lld
or ~libomptarget~lld.

This fixes it by changing also the default for libomptarget.

share/spack/gitlab/cloud_pipelines/stacks/data-vis-sdk/spack.yaml

@@ -25,7 +25,7 @@ spack:
     llvm:
       require: '@14:'
       # Minimize LLVM
-      variants: ~lldb~lld~polly~gold libunwind=none compiler-rt=none
+      variants: ~lldb~lld~libomptarget~polly~gold libunwind=none compiler-rt=none
     all:
       require: target=x86_64_v3