Fixes https://github.com/spring-projects/spring-integration/issues/3615
The `log()` operator for Java DSL in the end of flow causes a confusion
for its different behavior and, therefore, inconsistency with expectations
* Populate a `bridge()` in the end of flow instead of `nullChannel` when
the current component is `WireTapSpec` (relevant to `wireTap()` and `log()`)
* Deprecate a `logAndReply()` operator since its behavior is now included into the `log()` in the end if flow
* Fix tests to use just `log()` in the end from now on
* Fix `dsl.adoc` for the new `log()` behaviour in the end of flow
10ea577549