[Merged by Bors] - perf: remove @[simp] on Fintype.card_of{IsEmpty,Subsingleton}

[j-loreaux]

These lemmas only apply to Fintype.ofIsEmpty and Fintype.ofSubsingleton, but they're discrimination tree keys match any Fintype.card application. This forces Lean to attempt to unify the variables too often, especially because unification problems which introduce metavariables don't benefit from the same caching mechanisms. See Zulip

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[github-actions]

PR summary 5dbaecacd7

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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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.

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No changes to technical debt.

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).

[j-loreaux]

!bench

[leanprover-bot]

Here are the benchmark results for commit 5dbaeca.
The entire run failed.
Found no significant differences.

[fpvandoorn]

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• Build
• Lint style