Make teaching qualification duration optional

We want to do some final calculations on this so we need to bring back
the ability to set this to false. This will be reverted once we've done
the analysis.

app/lib/work_history_duration.rb

@@ -1,28 +1,46 @@
 # frozen_string_literal: true
 
 class WorkHistoryDuration
-  def initialize(application_form:, relation:)
+  def initialize(
+    application_form:,
+    relation:,
+    consider_teaching_qualification: true
+  )
     @application_form = application_form
     @relation =
       relation.where.not(start_date: nil).where.not(hours_per_week: nil)
+    @consider_teaching_qualification = consider_teaching_qualification
   end
 
-  def self.for_application_form(application_form)
+  def self.for_application_form(
+    application_form,
+    consider_teaching_qualification: true
+  )
     WorkHistoryDuration.new(
       application_form:,
       relation: application_form.work_histories,
+      consider_teaching_qualification:,
     )
   end
 
-  def self.for_ids(ids, application_form:)
+  def self.for_ids(
+    ids,
+    application_form:,
+    consider_teaching_qualification: true
+  )
     WorkHistoryDuration.new(
       application_form:,
       relation: application_form.work_histories.where(id: ids),
+      consider_teaching_qualification:,
     )
   end
 
-  def self.for_record(record)
-    for_ids([record.id], application_form: record.application_form)
+  def self.for_record(record, consider_teaching_qualification: true)
+    for_ids(
+      [record.id],
+      application_form: record.application_form,
+      consider_teaching_qualification:,
+    )
   end
 
   def count_months
@@ -59,7 +77,7 @@ def enough_to_skip_induction?
   AVERAGE_WEEKS_PER_MONTH = 4.34
   HOURS_PER_FULL_TIME_MONTH = 130.0
 
-  attr_reader :application_form, :relation
+  attr_reader :application_form, :relation, :consider_teaching_qualification
 
   def work_histories
     @work_histories ||=
@@ -71,7 +89,10 @@ def work_histories
   end
 
   def teaching_qualification
-    @teaching_qualification ||= application_form.teaching_qualification
+    @teaching_qualification ||=
+      if consider_teaching_qualification
+        application_form.teaching_qualification
+      end
   end
 
   def work_history_full_time_months(work_history)