Move `derailed_benchmarks` gem to default group

Some benchmarks of the gem require booting the app in `production`
environment.

Gemfile

@@ -315,6 +315,9 @@ gem 'peek-redis', '~> 1.2.0'
 # Snowplow events tracking
 gem 'snowplow-tracker', '~> 0.6.1'
 
+# Memory benchmarks
+gem 'derailed_benchmarks', require: false
+
 # Metrics
 group :metrics do
   gem 'method_source', '~> 0.8', require: false
@@ -389,7 +392,6 @@ group :development, :test do
   gem 'activerecord_sane_schema_dumper', '1.0'
 
   gem 'stackprof', '~> 0.2.10', require: false
-  gem 'derailed_benchmarks', require: false
 
   gem 'simple_po_parser', '~> 1.1.2', require: false