test: silence expected warnings/errors during test runs

Passes `capture_log: true` to ExUnit.start/1 so log output emitted
during a passing test stays in the per-test capture buffer instead of
stdout. Drops ~360 lines of noise from the suite: Postgrex teardown
disconnects, expected worker failures, NexradClient 404 stubs,
NotifyListener warm-skip messages, SNMP poll failures, PromEx tag-
drop warnings, and OTel-handler boot errors. Failing tests still
surface their full logs on report, so debugging is unchanged.

Side-effect fixes:
- LoggerFormatTest opts out via @moduletag capture_log: false — it
  patches the :default :logger handler and capture_log hot-swaps the
  same handler, so the setup lookup would 404.
- TelemetryTest.start_link/1 unlinks the supervisor before the brutal
  kill so the exit signal doesn't propagate to the test process.
- Drop unused `import Ecto.Query` in a top_hours mix-task test.
- Drop unused default-arg `attrs \\ %{}` on create_contact/1 in
  contact_map_live_test (every caller passes attrs explicitly).

Remaining noise is ~3 lines from oban_pro vendored-dep @impl warnings
(require an upstream patch) plus rare intermittent async teardowns.

test/microwaveprop/logger_format_test.exs

@@ -2,12 +2,18 @@ defmodule Microwaveprop.LoggerFormatTest do
   # async: false — we briefly swap the global :default :logger handler's
   # formatter and forward its output to a self()-bound IO device so the
   # test can capture the JSON-encoded output. Restored on exit.
+  #
+  # Opts out of the suite-wide capture_log flag — capture_log hot-swaps
+  # the :default handler for its own capture handler, so our direct
+  # :logger.get_handler_config(:default) lookup in setup would 404.
   use ExUnit.Case, async: false
 
   alias LoggerJSON.Formatters.Basic
 
   require Logger
 
+  @moduletag capture_log: false
+
   describe "structured JSON formatter" do
     setup do
       {:ok, handler_cfg} = :logger.get_handler_config(:default)

test/microwaveprop_web/live/contact_map_live_test.exs

@@ -6,7 +6,7 @@ defmodule MicrowavepropWeb.ContactMapLiveTest do
   alias Microwaveprop.Radio.Contact
   alias Microwaveprop.Repo
 
-  defp create_contact(attrs \\ %{}) do
+  defp create_contact(attrs) do
     default = %{
       station1: "W5XD",
       station2: "K5TR",

test/microwaveprop_web/telemetry_test.exs

@@ -93,8 +93,10 @@ defmodule MicrowavepropWeb.TelemetryTest do
       {:ok, pid} = Supervisor.start_link(Telemetry, :ok, name: sup_name)
       assert Process.alive?(pid)
 
-      on_exit = fn -> if Process.alive?(pid), do: Process.exit(pid, :kill) end
-      on_exit.()
+      # Unlink before tearing down so the brutal-kill exit signal doesn't
+      # propagate to the test process (which trap_exit defaults to off).
+      Process.unlink(pid)
+      Process.exit(pid, :kill)
     end
   end
 end

test/mix/tasks/simple_tasks_test.exs

@@ -118,8 +118,6 @@ defmodule Mix.Tasks.SimpleTasksTest do
     end
 
     test "enqueues jobs for the top hours when contacts exist" do
-      import Ecto.Query
-
       # Seed one contact so top_hours_by_contact_count returns something.
       {:ok, _contact} =
         %Contact{}

test/test_helper.exs

@@ -1,2 +1,2 @@
-ExUnit.start(exclude: [:slow])
+ExUnit.start(exclude: [:slow], capture_log: true)
 Ecto.Adapters.SQL.Sandbox.mode(Microwaveprop.Repo, :manual)