Remove unneeded address#first_lines method

Used to be used to supply address one and two as one line to
CCMS but does not appear to be necessary.

app/models/address.rb

@@ -25,10 +25,6 @@ def pretty_postcode?
     postcode[-4] == " "
   end
 
-  def first_lines
-    [address_line_one, address_line_two].select(&:present?).join(" ")
-  end
-
   def to_json(*_args)
     {
       address_line_one:,

spec/models/address_spec.rb

@@ -46,20 +46,4 @@
     model.postcode = "SW1H9AJ"
     expect(model.pretty_postcode).to eq("SW1H 9AJ")
   end
-
-  context "when the address has lines one and two populated" do
-    it "first_lines displays the first two lines of the address concatenated" do
-      model.address_line_one = "102"
-      model.address_line_two = "Petty France"
-      expect(model.first_lines).to eq("102 Petty France")
-    end
-  end
-
-  context "when the address has only line one populated" do
-    it "first_lines displays only the first line of the address" do
-      model.address_line_one = "102"
-      model.address_line_two = nil
-      expect(model.first_lines).to eq("102")
-    end
-  end
 end