Ref:

- 33f3ccd6ae/CHANGELOG.md (L134-L136)
- 7165d3fa58/appservice/registration.go (L30)

Intentionally not removing the old configuration setting yet, as some bridges may/do not support
the new setting name. It's likely just bridgev2 mautrix bridges that have been updated and support both right now.

Since mautrix-whatsapp v0.12.0, the bridge deals with more than just phone numbers now,
so it sometimes tries to manage users with Matrix IDs like: `@whatsapp_lid-123456789:example.com`

Ref:

- https://github.com/mautrix/whatsapp/releases/tag/v0.12.0
- https://mau.fi/blog/2025-04-mautrix-release/

Signed-off-by: HarHarLinks <2803622+HarHarLinks@users.noreply.github.com>

Ref: https://openai.com/index/gpt-4-1/

* Add matrix_bridges_msc4190_enabled flag for using msc4190 on supported mautrix bridges.

* Apply to_json to msc4190 in mautrix configs

* Add | to_json to mautrix bridge registration io.element.msc4190.

* require matrix_synapse_experimental_features_msc3202_device_masquerading_enabled for matrix_bridges_msc4190_enabled

* Also add msc4190 support for mautrix-telegram

Now that https://github.com/element-hq/element-web/pull/29471
is part of v1.11.96, we don't need to carry around this custom workaround.

This also reverts e5574a405e because:
- it was causing issues on some servers (not clear why)
- such workarounds are no longer necessary when doing multi-stage building.

This is a security patch for Synapse that fixes an actively exploited bug.