Remove the 'shorthand' option from `tests.server.make_request`

This issue has been migrated from [#12103](https://github.com/matrix-org/synapse/issues/12103).

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With Matrix 1.1 came the [decoupling of Client API endpoint versions from the overall spec version](https://spec.matrix.org/v1.2/#endpoint-versioning). This means that individual CS APIs can now have their own version (i.e. `/_matrix/client/v3/login` vs. `/_matrix/client/v4/profile`).

This conflicts with the assumption made by the default enabled `shorthand` option of `tests.server.make_request`, which prepends `/_matrix/client/r0/` to request paths if a prefix is not already specified.

https://github.com/matrix-org/synapse/blob/807efd26aec9b65c6a2f02d10fd139095a5b3387/tests/server.py#L271-L272

https://github.com/matrix-org/synapse/blob/807efd26aec9b65c6a2f02d10fd139095a5b3387/tests/server.py#L293-L301

This cannot simply be updated from `/r0` to `/v3`, as that will be invalid as soon as one of the many CS APIs updates its version. Instead, I propose the option be removed, and all calls to the endpoint be updated to include the correct path prefix.