fix: Remove duplicate / character on the proxy route (#10404)

The proxy method adds an extra slash even if the route param has the
character. It’s challenging to check the expected format on each route.
The simplest solution is to check if the route param begins with a
slash, and if not, append one.

NB: The existing tests are sufficient to cover this case. There’s no
need for an additional test to specifically test this.

app/controllers/api/v1/accounts/integrations/captain_controller.rb

@@ -18,11 +18,11 @@ class Api::V1::Accounts::Integrations::CaptainController < Api::V1::Accounts::Ba
   end
 
   def request_path
-    if params[:route] == '/sessions/profile'
-      'api/sessions/profile'
-    else
-      "api/accounts/#{hook.settings['account_id']}/#{params[:route]}"
-    end
+    request_route = with_leading_hash_on_route(params[:route])
+
+    return 'api/sessions/profile' if request_route == '/sessions/profile'
+
+    "api/accounts/#{hook.settings['account_id']}#{request_route}"
   end
 
   def request_url
@@ -41,6 +41,12 @@ class Api::V1::Accounts::Integrations::CaptainController < Api::V1::Accounts::Ba
     method
   end
 
+  def with_leading_hash_on_route(request_route)
+    return '' if request_route.blank?
+
+    request_route.start_with?('/') ? request_route : "/#{request_route}"
+  end
+
   def permitted_params
     params.permit(:method, :route, body: {})
   end