[Insights] Change the default weeks period limit to 12

Signed-off-by: Rémy Coutable <remy@rymai.me>

ee/changelogs/unreleased/change-defaults-insights-period.yml

+---
+title: "[Insights] Change the default weeks period limit to 12"
+merge_request: 11498
+author:
+type: changed

ee/lib/gitlab/insights/finders/issuable_finder.rb

@@ -16,7 +16,7 @@ module Gitlab
         }.with_indifferent_access.freeze
         PERIODS = {
           days: { default: 30 },
-          weeks: { default: 4 },
+          weeks: { default: 12 },
           months: { default: 12 }
         }.with_indifferent_access.freeze
 

ee/spec/lib/gitlab/insights/finders/issuable_finder_spec.rb

@@ -93,7 +93,7 @@ RSpec.describe Gitlab::Insights::Finders::IssuableFinder do
             opts.merge!(group_by: 'week')
           end
 
-          it 'returns issuable created after 4 weeks ago' do
+          it 'returns issuable created after 12 weeks ago' do
             expect(subject.to_a).to eq([issuable2, issuable3, issuable4])
           end
         end
@@ -219,8 +219,8 @@ RSpec.describe Gitlab::Insights::Finders::IssuableFinder do
       context 'with group_by: "week"' do
         let(:opts) { base_opts.merge!(group_by: 'week') }
 
-        it 'returns 4' do
-          expect(subject).to eq(4)
+        it 'returns 12' do
+          expect(subject).to eq(12)
         end
       end