SCP-3096 - Remove wallet proxy

[silky]

Don't proxy the wallet backend through our webserver anymore.

Fixes SCP-3096

TODO:

• When we do a release of plutus-starter, update that endpoint call as well.

The main change here is curl calls like this:

> curl -s -d '' http://localhost:9080/wallet/create

go direct to the wallet server instead:

> curl -s -d '' http://localhost:9081/create

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