The `ignore` parameter was only used for `spack activate/deactivate`, and it isn't used
by Spack Environments which have their own handling of file conflicts. We should remove it.
Everything that handles `ignore=` was removed in #29317 and included in 0.19, when we
removed `spack activate` and `spack deactivate` in favor of environments. So all of these
usages removed here were already being ignored by Spack.
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