[v24.2.x] rpk: only include tuner package files in linux builds

[vbotbuildovich]

Backport #25158 to branch v24.2.x. This issue was created as a placeholder because the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v24.2.x
git checkout -b manual-backport-25158-v24.2.x-712
git cherry-pick -x 23333bef96

git push origin manual-backport-25158-v24.2.x-712
gh pr create \
  --title "[v24.2.x] rpk: only include tuner package files in linux builds" \
  --base "v24.2.x" \
  --label "kind/backport" \
  --head "manual-backport-25158-v24.2.x-712" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --milestone "v24.2.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/25158 "

JIRA Link: [CORE-9206](https://redpandadata.atlassian.net/browse/CORE-9206)