Remove parity check service and ECF integration points

Remove parity check service, remaining ECF models and views.

Revert rack_attack to be enabled in migration.

Remove gems used for parity check.

Remove ECF schema and databse connection.

Gemfile

@@ -10,13 +10,11 @@ gem "canonical-rails"
 gem "countries"
 gem "cssbundling-rails", "~> 1.4"
 gem "daemons"
-gem "deepsort"
 gem "delayed_cron_job"
 gem "delayed_job", "~> 4.1"
 gem "delayed_job_active_record"
 gem "delayed_job_web"
 gem "devise", "~> 4.9"
-gem "diffy"
 # gem 'dfe-analytics', github: 'DFE-Digital/dfe-analytics', tag: 'v1.14.2'
 # temporary until PR will be accepted
 gem "dfe-analytics", github: "slawosz/dfe-analytics", branch: "allow-to-exclude-models"
@@ -49,7 +47,6 @@ gem "rails_semantic_logger"
 gem "redis"
 gem "rouge"
 gem "rubyzip"
-gem "scenic"
 gem "secure_headers"
 gem "sentry-delayed_job"
 gem "sentry-rails"

Gemfile.lock

@@ -161,7 +161,6 @@ GEM
     daemons (1.4.1)
     date (3.4.0)
     declarative (0.0.20)
-    deepsort (0.5.0)
     delayed_cron_job (0.9.0)
       fugit (>= 1.5)
     delayed_job (4.1.13)
@@ -183,7 +182,6 @@ GEM
       responders
       warden (~> 1.2.3)
     diff-lcs (1.5.1)
-    diffy (3.4.3)
     docile (1.4.0)
     dotenv (3.1.3)
     dotenv-rails (3.1.3)
@@ -569,9 +567,6 @@ GEM
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    scenic (1.8.0)
-      activerecord (>= 4.0.0)
-      railties (>= 4.0.0)
     scss_lint (0.59.0)
       sass (~> 3.5, >= 3.5.5)
     scss_lint-govuk (0.2.0)
@@ -706,14 +701,12 @@ DEPENDENCIES
   countries
   cssbundling-rails (~> 1.4)
   daemons
-  deepsort
   delayed_cron_job
   delayed_job (~> 4.1)
   delayed_job_active_record
   delayed_job_web
   devise (~> 4.9)
   dfe-analytics!
-  diffy
   dotenv-rails
   email_validator
   factory_bot_rails
@@ -760,7 +753,6 @@ DEPENDENCIES
   rswag-specs
   rubocop-govuk
   rubyzip
-  scenic
   scss_lint-govuk
   secure_headers
   selenium-webdriver