Use Unix Time for Jira update sequence id

Monotonic Time counts the number of seconds since
system boot. This means it resets with every deploy
and can be different in each processes. Unix Time
counts the number of seconds since 1970-1-1 UTC.

changelogs/unreleased/229174_use_unix_time_for_jira_update_sequence_id.yml

+---
+title: Change Jira Connect update sequence id to use Unix Time
+merge_request: 51697
+author:
+type: fixed

lib/atlassian/jira_connect/client.rb

@@ -4,7 +4,7 @@ module Atlassian
   module JiraConnect
     class Client < Gitlab::HTTP
       def self.generate_update_sequence_id
-        Gitlab::Metrics::System.monotonic_time.to_i
+        (Time.now.utc.to_f * 1000).round
       end
 
       def initialize(base_uri, shared_secret)

spec/lib/atlassian/jira_connect/client_spec.rb

@@ -18,15 +18,15 @@ RSpec.describe Atlassian::JiraConnect::Client do
     end
   end
 
-  around do |example|
-    freeze_time { example.run }
-  end
-
   describe '.generate_update_sequence_id' do
-    it 'returns monotonic_time converted it to integer' do
-      allow(Gitlab::Metrics::System).to receive(:monotonic_time).and_return(1.0)
+    it 'returns unix time in microseconds as integer', :aggregate_failures do
+      travel_to(Time.utc(1970, 1, 1, 0, 0, 1)) do
+        expect(described_class.generate_update_sequence_id).to eq(1000)
+      end
 
-      expect(described_class.generate_update_sequence_id).to eq(1)
+      travel_to(Time.utc(1970, 1, 1, 0, 0, 5)) do
+        expect(described_class.generate_update_sequence_id).to eq(5000)
+      end
     end
   end