Reduce number mass inserts

When we run fixtures for CI we do not need masive mass
inserts and also for almost all cases we do not need to
involve mass inserts into other fixtures unless specifically
designed so or that increases fixture run times dramatically

db/fixtures/development/02_users.rb

@@ -4,7 +4,7 @@ class Gitlab::Seeder::Users
   include ActionView::Helpers::NumberHelper
 
   RANDOM_USERS_COUNT = 20
-  MASS_NAMESPACES_COUNT = 100
+  MASS_NAMESPACES_COUNT = ENV['CI'] ? 1 : 100
   MASS_USERS_COUNT = ENV['CI'] ? 10 : 1_000_000
   attr_reader :opts
 

db/fixtures/development/03_project_3_features.rb

@@ -13,7 +13,7 @@ class Gitlab::Seeder::ProjectFeatures
     Gitlab::Seeder.with_mass_insert(Project.count, "Project features") do
       Project.each_batch(of: BATCH_SIZE) do |batch, index|
         range = batch.pluck(Arel.sql('MIN(id)'), Arel.sql('MAX(id)')).first
-        count = index * BATCH_SIZE
+        count = index * batch.size
 
         Gitlab::Seeder.log_message("Creating project features: #{count}.")
         ActiveRecord::Base.connection.execute <<~SQL

db/fixtures/development/03_project_4_routes.rb

@@ -13,7 +13,7 @@ class Gitlab::Seeder::ProjectRoutes
     Gitlab::Seeder.with_mass_insert(Project.count, "Project routes") do
       Project.each_batch(of: BATCH_SIZE / 2) do |batch, index|
         range = batch.pluck(Arel.sql('MIN(id)'), Arel.sql('MAX(id)')).first
-        count = index * BATCH_SIZE / 2
+        count = index * batch.size
 
         Gitlab::Seeder.log_message("Creating project routes: #{count}.")
         ActiveRecord::Base.connection.execute <<~SQL

ee/db/fixtures/development/90_productivity_analytics.rb

@@ -139,7 +139,7 @@ Gitlab::Seeder.quiet do
   flag = 'SEED_PRODUCTIVITY_ANALYTICS'
 
   if ENV[flag]
-    Project.find_each do |project|
+    Project.not_mass_generated.find_each do |project|
       # This seed naively assumes that every project has a repository, and every
       # repository has a `master` branch, which may be the case for a pristine
       # GDK seed, but is almost never true for a GDK that's actually had