Cleanup undefined severity and confidence level from code

ee/app/models/vulnerabilities/occurrence.rb

@@ -39,7 +39,7 @@ module Vulnerabilities
     }.with_indifferent_access.freeze
 
     SEVERITY_LEVELS = {
-      undefined: 0,
+      # undefined: 0, no longer applicable
       info: 1,
       unknown: 2,
       # experimental: 3, formerly used by confidence, no longer applicable

ee/app/services/security/dependency_list_service.rb

@@ -72,8 +72,8 @@ module Security
     # will have highest severity
     def sort_by_severity(collection)
       collection.sort do |dep_i, dep_j|
-        level_i = dep_i.dig(:vulnerabilities, 0, :severity) || :undefined
-        level_j = dep_j.dig(:vulnerabilities, 0, :severity) || :undefined
+        level_i = dep_i.dig(:vulnerabilities, 0, :severity) || :unknown
+        level_j = dep_j.dig(:vulnerabilities, 0, :severity) || :unknown
 
         ::Vulnerabilities::Occurrence::SEVERITY_LEVELS[level_j] <=> ::Vulnerabilities::Occurrence::SEVERITY_LEVELS[level_i]
       end

ee/lib/api/vulnerability_findings.rb

@@ -41,7 +41,7 @@ module API
         optional :severity,
                  type: Array[String],
                  desc: 'Returns vulnerabilities belonging to specified severity level: '\
-                       '`undefined`, `info`, `unknown`, `low`, `medium`, `high`, or `critical`. Defaults to all',
+                       '`info`, `unknown`, `low`, `medium`, `high`, or `critical`. Defaults to all',
                  values: ::Vulnerabilities::Occurrence.severities.keys,
                  default: ::Vulnerabilities::Occurrence.severities.keys
         optional :confidence,

ee/lib/gitlab/vulnerabilities/history.rb

@@ -29,7 +29,7 @@ module Gitlab
       end
 
       def cached_vulnerability_history
-        history = { undefined: {}, info: {}, unknown: {}, low: {}, medium: {}, high: {}, critical: {}, total: {} }
+        history = { info: {}, unknown: {}, low: {}, medium: {}, high: {}, critical: {}, total: {} }
 
         project_ids_to_fetch.each do |project_id|
           project_history = Gitlab::Vulnerabilities::HistoryCache.new(vulnerable, project_id).fetch(HISTORY_RANGE)

ee/lib/gitlab/vulnerabilities/summary.rb

@@ -21,7 +21,6 @@ module Gitlab
 
       def cached_vulnerability_summary
         summary = {
-          undefined: 0,
           info:      0,
           unknown:   0,
           low:       0,

ee/spec/controllers/groups/security/vulnerability_findings_controller_spec.rb

@@ -103,7 +103,6 @@ describe Groups::Security::VulnerabilityFindingsController do
       end
 
       expect(json_response).to eq({
-        "undefined" => {},
         "info" => {},
         "unknown" => {},
         "low" => {},

ee/spec/controllers/projects/dependencies_controller_spec.rb

@@ -117,7 +117,7 @@ describe Projects::DependenciesController do
 
                 it 'returns sorted list' do
                   expect(json_response['dependencies'].first['name']).to eq('nokogiri')
-                  expect(json_response['dependencies'].second['name']).to eq('debug')
+                  expect(json_response['dependencies'].second['name']).to eq('mini_portile2')
                 end
               end
             end

ee/spec/models/vulnerability_spec.rb

@@ -4,7 +4,7 @@ require 'spec_helper'
 
 describe Vulnerability do
   let(:state_values) { { detected: 1, dismissed: 2, resolved: 3, confirmed: 4 } }
-  let(:severity_values) { { undefined: 0, info: 1, unknown: 2, low: 4, medium: 5, high: 6, critical: 7 } }
+  let(:severity_values) { { info: 1, unknown: 2, low: 4, medium: 5, high: 6, critical: 7 } }
 
   let(:confidence_values) do
     { undefined: 0, ignore: 1, unknown: 2, experimental: 3, low: 4, medium: 5, high: 6, confirmed: 7 }

ee/spec/requests/security/vulnerability_findings_spec.rb

@@ -302,7 +302,6 @@ describe 'GET /-/security/vulnerability_findings/history' do
       end
 
       expect(json_response).to eq({
-        "undefined" => {},
         "info" => {},
         "unknown" => {},
         "low" => {},