fix(portal): Only configure Sentry.LoggerHandler once (#8025)

The applications within our umbrella are all joined into a single Erlang
cluster, and logger configuration is applied already to the entire
umbrella.

As such, registering the Sentry log handler in each application's
startup routine triggers duplicate handlers to be registered for the
cluster, resulting in warnings like this in GCP:

```
Event dropped due to being a duplicate of a previously-captured event.
```

As such, we can move the log handler configuration to the top-level
`:logger` key, under the `:logger` subkey for configuring a single
handler. We then load this handler config in the `domain` app only and
it applies to the entire cluster.

elixir/apps/api/lib/api/application.ex

@@ -6,8 +6,6 @@ defmodule API.Application do
     _ = :opentelemetry_cowboy.setup()
     _ = OpentelemetryPhoenix.setup(adapter: :cowboy2)
 
-    Logger.add_handlers(:api)
-
     children = [
       API.Endpoint
     ]

elixir/apps/domain/lib/domain/application.ex

@@ -8,7 +8,7 @@ defmodule Domain.Application do
     _ = OpentelemetryLoggerMetadata.setup()
     _ = OpentelemetryEcto.setup([:domain, :repo])
 
-    Logger.add_handlers(:domain)
+    Logger.add_handlers(:logger)
 
     # Can be uncommented when this bug is fixed: https://github.com/open-telemetry/opentelemetry-erlang-contrib/issues/327
     # _ = OpentelemetryFinch.setup()

elixir/apps/web/lib/web/application.ex

@@ -7,8 +7,6 @@ defmodule Web.Application do
     _ = :opentelemetry_cowboy.setup()
     _ = OpentelemetryPhoenix.setup(adapter: :cowboy2)
 
-    Logger.add_handlers(:web)
-
     children = [
       Web.Endpoint
     ]

elixir/config/config.exs

@@ -12,17 +12,6 @@ import Config
 ##### Domain ##################
 ###############################
 
-config :domain, :logger, [
-  {:handler, :domain, Sentry.LoggerHandler,
-   %{
-     config: %{
-       level: :warning,
-       metadata: :all,
-       capture_log_messages: true
-     }
-   }}
-]
-
 config :domain, ecto_repos: [Domain.Repo]
 config :domain, generators: [binary_id: true, context_app: :domain]
 
@@ -128,17 +117,6 @@ config :domain, web_external_url: "http://localhost:13000"
 ##### Web #####################
 ###############################
 
-config :web, :logger, [
-  {:handler, :web, Sentry.LoggerHandler,
-   %{
-     config: %{
-       level: :warning,
-       metadata: :all,
-       capture_log_messages: true
-     }
-   }}
-]
-
 config :web, ecto_repos: [Domain.Repo]
 config :web, generators: [binary_id: true, context_app: :domain]
 config :web, client_handler: "firezone-fd0020211111://"
@@ -254,6 +232,17 @@ config :logger, :default_formatter,
   format: "$time $metadata[$level] $message\n",
   metadata: :all
 
+config :logger, :logger, [
+  {:handler, :sentry, Sentry.LoggerHandler,
+   %{
+     config: %{
+       level: :warning,
+       metadata: :all,
+       capture_log_messages: true
+     }
+   }}
+]
+
 # Use Jason for JSON parsing in Phoenix
 config :phoenix, :json_library, Jason