Fixed styling per Rubocop pedantics

lib/gitlab/database/migration_helpers.rb

@@ -119,7 +119,9 @@ module Gitlab
           transaction do
             update_column_in_batches(table, column, default)
           end
-        rescue Exception => error
+        # We want to rescue _all_ exceptions here, even those that don't inherit
+        # from StandardError.
+        rescue Exception => error # rubocop: disable all
           remove_column(table, column)
 
           raise error

spec/lib/gitlab/database/migration_helpers_spec.rb

@@ -105,9 +105,9 @@ describe Gitlab::Database::MigrationHelpers, lib: true do
         expect(model).to receive(:remove_column).
           with(:projects, :foo)
 
-        expect {
+        expect do
           model.add_column_with_default(:projects, :foo, :integer, default: 10)
-        }.to raise_error(RuntimeError)
+        end.to raise_error(RuntimeError)
       end
     end
 
@@ -115,9 +115,9 @@ describe Gitlab::Database::MigrationHelpers, lib: true do
       it 'raises RuntimeError' do
         expect(model).to receive(:transaction_open?).and_return(true)
 
-        expect {
+        expect do
           model.add_column_with_default(:projects, :foo, :integer, default: 10)
-        }.to raise_error(RuntimeError)
+        end.to raise_error(RuntimeError)
       end
     end
   end