Remove un-used code

This rake task was used by pre-Cells 1.0 development, but we have since
switched to Cells 1.0

.rubocop_todo/rspec/example_wording.yml

@@ -63,7 +63,6 @@ RSpec/ExampleWording:
     - 'spec/support/shared_examples/quick_actions/issuable/max_issuable_examples.rb'
     - 'spec/support/shared_examples/services/migrate_to_ghost_user_service_shared_examples.rb'
     - 'spec/support/shared_examples/uploaders/upload_type_shared_examples.rb'
-    - 'spec/tasks/gitlab/db/cells/bump_cell_sequences_rake_spec.rb'
     - 'spec/tasks/gitlab/db/decomposition/rollback/bump_ci_sequences_rake_spec.rb'
     - 'spec/tooling/lib/tooling/api/job_spec.rb'
     - 'spec/uploaders/dependency_proxy/file_uploader_spec.rb'

lib/tasks/gitlab/db/cells/bump_cell_sequences.rake

-# frozen_string_literal: true
-
-namespace :gitlab do
-  namespace :db do
-    namespace :cells do
-      desc 'Bump sequences for cell-local tables on the cells database'
-      task :bump_cell_sequences, [:increase_by] => :environment do |_t, args|
-        # We do not want to run this on production environment, even accidentally.
-        unless Gitlab.dev_or_test_env?
-          puts Rainbow('This rake task cannot be run in production environment').red
-          exit 1
-        end
-
-        increase_by = args.increase_by.to_i
-        if increase_by < 1
-          puts Rainbow('Please specify a positive integer `increase_by` value').red
-          puts Rainbow('Example: rake gitlab:db:cells:bump_cell_sequences[100000]').green
-          exit 1
-        end
-
-        Gitlab::Database::BumpSequences.new(:gitlab_main_cell, increase_by).execute
-      end
-    end
-  end
-end

spec/tasks/gitlab/db/cells/bump_cell_sequences_rake_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-RSpec.describe 'gitlab:db:cells:bump_cell_sequences', :silence_stdout,
-  :suppress_gitlab_schemas_validate_connection, feature_category: :cell, query_analyzers: false do
-  before(:all) do
-    Rake.application.rake_require 'tasks/gitlab/db/cells/bump_cell_sequences'
-  end
-
-  let(:main_sequence_name) { 'users_id_seq' }
-  let(:main_cell_sequence_name) { 'namespaces_id_seq' }
-
-  # This is just to make sure that all of the sequences start with `is_called=True`
-  # which means that the next call to nextval() is going to increment the sequence.
-  # To give predictable test results.
-  before do
-    ApplicationRecord.connection.select_value("select nextval($1)", nil, [main_cell_sequence_name])
-  end
-
-  context 'when run in production environment' do
-    let(:expected_error_message) do
-      <<~HEREDOC
-        This rake task cannot be run in production environment
-      HEREDOC
-    end
-
-    it 'will print error message and exit' do
-      allow(Gitlab).to receive(:dev_or_test_env?).and_return(false)
-
-      expect do
-        run_rake_task('gitlab:db:cells:bump_cell_sequences', '10')
-      end.to raise_error(SystemExit) { |error| expect(error.status).to eq(1) }
-      .and output(expected_error_message).to_stdout
-    end
-  end
-
-  context 'when passing wrong argument' do
-    let(:expected_error_message) do
-      <<~HEREDOC
-        Please specify a positive integer `increase_by` value
-        Example: rake gitlab:db:cells:bump_cell_sequences[100000]
-      HEREDOC
-    end
-
-    it 'will print an error message and exit when passing no argument' do
-      expect do
-        run_rake_task('gitlab:db:cells:bump_cell_sequences')
-      end.to raise_error(SystemExit) { |error| expect(error.status).to eq(1) }
-      .and output(expected_error_message).to_stdout
-    end
-
-    it 'will print an error message and exit when passing a non positive integer value' do
-      expect do
-        run_rake_task('gitlab:db:cells:bump_cell_sequences', '-5')
-      end.to raise_error(SystemExit) { |error| expect(error.status).to eq(1) }
-      .and output(expected_error_message).to_stdout
-    end
-  end
-
-  context 'when bumping the sequences' do
-    it 'increments the sequence of the tables in the given schema, but not in other schemas' do
-      expect do
-        run_rake_task('gitlab:db:cells:bump_cell_sequences', '10')
-      end.to change {
-        last_value_of_sequence(ApplicationRecord.connection, main_sequence_name)
-      }.by(0)
-      .and change {
-        last_value_of_sequence(ApplicationRecord.connection, main_cell_sequence_name)
-      }.by(11) # the +1 is because the sequence has is_called = true
-    end
-  end
-end
-
-def last_value_of_sequence(connection, sequence_name)
-  allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/408220') do
-    connection.select_value("select last_value from #{sequence_name}")
-  end
-end