Remove Service#template? method

This is a boolean column so we can remove this method. Rails defined
automatically #{attribute}? methods.

app/models/service.rb

@@ -32,7 +32,7 @@ class Service < ApplicationRecord
   belongs_to :project, inverse_of: :services
   has_one :service_hook
 
-  validates :project_id, presence: true, unless: proc { |service| service.template? }
+  validates :project_id, presence: true, unless: -> { template? }
   validates :type, presence: true
 
   scope :visible, -> { where.not(type: 'GitlabIssueTrackerService') }
@@ -70,10 +70,6 @@ class Service < ApplicationRecord
     true
   end
 
-  def template?
-    template
-  end
-
   def category
     read_attribute(:category).to_sym
   end

spec/models/service_spec.rb

@@ -10,8 +10,13 @@ describe Service do
     it { is_expected.to have_one :issue_tracker_data }
   end
 
-  describe 'Validations' do
+  describe 'validations' do
     it { is_expected.to validate_presence_of(:type) }
+
+    it 'validates presence of project_id if not template', :aggregate_failures do
+      expect(build(:service, project_id: nil, template: true)).to be_valid
+      expect(build(:service, project_id: nil, template: false)).to be_invalid
+    end
   end
 
   describe 'Scopes' do