refactor: change the format of `Repr (Equiv.Perm α)` from `{c[0, 1], c[2, 3]}` to `c[0, 1] * c[2, 3]`

[Komyyy]

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• [ ] depends on: #12610

[github-actions[bot]]

PR summary d02bb2436e

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).

[mathlib4-dependent-issues-bot]

This PR/issue depends on:

• ~~leanprover-community/mathlib4#12610~~ By Dependent Issues (🤖). Happy coding!

[github-actions[bot]]

🚀 Pull request has been placed on the maintainer queue by YaelDillies.

[mathlib-bors[bot]]

Pull request successfully merged into master.

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