We log the entire signal data when it arrives from status-go in the native
layer, where our Clojure logging mechanism is unavailable. Sometimes, the
developer may not want that much noise during development, e.g. when managing
integration or contract tests.
This commit removes the native calls to log signals and adds a timbre
(log/debug ...) call in the event handler :signals/signal-received. We know
timbre will elide log calls at compile time given the minimum log level set,
therefore, we don't need to worry about performance because we will log signals
at the debug level only.