Remove observer_cli from CLI escritps

observer_cli (and its dependency recon) was declared as a dependency
of rabbitmq_cli and as a consequence included in all escritps. However
the major part of observer_cli runs in the broker. The cli side only
used `observer_cli:rpc_start/2` which is just an rpc call into the
target node.

By using common rpc call we can remove observer_cli and recon from the
escripts. This can be considered a minor improvement based on the
philosophy "simpler is better".

As an additional benefit auto-completing functions of the recon app
now works in `rabbitmq-diagnostics remote_shell`.
(eg. `recon:proc_c<TAB>`)

deps/rabbitmq_cli/Makefile

@@ -1,7 +1,7 @@
 PROJECT = rabbitmq_cli
 
 BUILD_DEPS = rabbit_common
-DEPS = csv json observer_cli stdout_formatter
+DEPS = csv json stdout_formatter
 TEST_DEPS = amqp amqp_client temp x509 rabbit
 
 dep_amqp = hex 3.3.0

deps/rabbitmq_cli/lib/rabbitmq/cli/diagnostics/commands/observer_command.ex

@@ -19,11 +19,7 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.ObserverCommand do
 
   @dialyzer {:nowarn_function, run: 2}
   def run([], %{node: node_name, interval: interval}) do
-    case :observer_cli.start(node_name, [{:interval, interval * 1000}]) do
-      # See zhongwencool/observer_cli#54
-      {:badrpc, _} = err -> err
-      {:error, _} = err -> err
-      {:error, _, _} = err -> err
+    case :rabbit_misc.rpc_call(node_name, :observer_cli, :start, [interval * 1000], :infinity) do
       :ok -> {:ok, "Disconnected from #{node_name}."}
       :quit -> {:ok, "Disconnected from #{node_name}."}
       other -> other

deps/rabbitmq_cli/mix.exs

@@ -29,7 +29,6 @@ defmodule RabbitMQCtl.MixfileBase do
           JSON,
           :mnesia,
           :msacc,
-          :observer_cli,
           :public_key,
           :pubkey_cert,
           :rabbit,
@@ -157,11 +156,6 @@ defmodule RabbitMQCtl.MixfileBase do
         path: Path.join(deps_dir, "stdout_formatter"),
         compile: if(is_bazel, do: fake_cmd, else: make_cmd)
       },
-      {
-        :observer_cli,
-        path: Path.join(deps_dir, "observer_cli"),
-        compile: if(is_bazel, do: fake_cmd, else: make_cmd)
-      },
       {
         :rabbit_common,
         path: Path.join(deps_dir, "rabbit_common"),