Change routes.payload.multipart to false by default

[hueniverse]

No description provided.

[roderik]

For people finding this issue, at this time the @types/hapi typescript types are still at 18.0.3 which does not accept true.

As an ugly workaround you can do

      payload: {
        output: 'stream',
        parse: true,
        allow: 'multipart/form-data',
        multipart: true,
      } as any,