DEV: Drop deprecated Badge#image column (#25536)

We just completed the 3.2 release, which marks a good time to drop some previously deprecated columns.

Since the column has been marked in ignored_columns, it has been inaccessible to application code since then. There's a tiny risk that this might break a Data Explorer query, but given the nature of the column, the years of disuse, and the fact that such a breakage wouldn't be critical, we accept it.

spec/jobs/migrate_badge_image_to_uploads_spec.rb

@@ -1,58 +0,0 @@
-# frozen_string_literal: true
-
-RSpec.describe Jobs::MigrateBadgeImageToUploads do
-  let(:image_url) { "https://omg.aws.somestack/test.png" }
-  let(:badge) { Fabricate(:badge) }
-
-  before do
-    @orig_logger = Rails.logger
-    Rails.logger = @fake_logger = FakeLogger.new
-  end
-
-  after { Rails.logger = @orig_logger }
-
-  it "should migrate to the new badge `image_upload_id` column correctly" do
-    stub_request(:get, image_url).to_return(
-      status: 200,
-      body: file_from_fixtures("smallest.png").read,
-    )
-    DB.exec(<<~SQL, flair_url: image_url, id: badge.id)
-      UPDATE badges SET image = :flair_url WHERE id = :id
-    SQL
-
-    expect do described_class.new.execute_onceoff({}) end.to change { Upload.count }.by(1)
-
-    badge.reload
-    upload = Upload.last
-    expect(badge.image_upload).to eq(upload)
-    expect(badge.image_url).to eq(upload.url)
-    expect(badge[:image]).to eq(nil)
-  end
-
-  it "should skip badges with invalid flair URLs" do
-    DB.exec("UPDATE badges SET image = 'abc' WHERE id = ?", badge.id)
-    described_class.new.execute_onceoff({})
-    expect(@fake_logger.warnings.count).to eq(0)
-    expect(@fake_logger.errors.count).to eq(0)
-  end
-
-  # this case has a couple of hacks that are needed to test this behavior, so if it
-  # starts failing randomly in the future, I'd just delete it and not bother with it
-  it "should not keep retrying forever if download fails" do
-    stub_request(:get, image_url).to_return(status: 403)
-    instance = described_class.new
-    instance.expects(:sleep).times(2)
-
-    DB.exec(<<~SQL, flair_url: image_url, id: badge.id)
-      UPDATE badges SET image = :flair_url WHERE id = :id
-    SQL
-
-    expect do instance.execute_onceoff({}) end.not_to change { Upload.count }
-
-    badge.reload
-    expect(badge.image_upload).to eq(nil)
-    expect(badge.image_url).to eq(nil)
-    expect(Badge.where(id: badge.id).select(:image).first[:image]).to eq(image_url)
-    expect(@fake_logger.warnings.count).to eq(3)
-  end
-end