[Merged by Bors] - chore: remove porting notes about the nonempty instance linter

[kim-em]

Zulip thread

[kim-em]

Closes #5171

[github-actions]

PR summary 8e5b5529fd

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

---

Decrease in tech debt: (relative, absolute) = (162.00, 0.04)

Current number	Change	Type
4406	-162	porting notes

Current commit 8e5b5529fd
Reference commit 3bf4857ada

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[grunweg]

The diff does what it says. Can you take a step back and tell us why this is fine to remove?

• Is there documentation what the linter did in mathlib3? Is that functionality incorporated into Lean core/ unnecessary somehow?
  (If not, a better fix seems to be porting the linter to mathlib4. Is there are instructions what it does, I could try this myself.)
• If the linter is going to be re-porting, having those comments could be helpful, right? (At least, manually having to add this attribute 200 times will be annoying.) Or is your argument that one should re-audit all those locations anyway, so removing those notes now is fine?

[bryangingechen]

(I've added the Zulip link to the PR description / eventual commit message.)

[grunweg]

Thanks! Makes much more sense now.

[jcommelin]

bors d+

[mathlib-bors]

✌️ kim-em can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[kim-em]

bors merge

[mathlib-bors]

👎 Rejected by label

[kim-em]

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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