Rename #calculate_checksum! to #verify

This helps to differentiate `VerifiableReplicator#verify` from
`ReplicableModel#calculate_checksum!`.

ee/app/models/concerns/geo/verifiable_replicator.rb

@@ -50,7 +50,7 @@ module Geo
       schedule_checksum_calculation if needs_checksum?
     end
 
-    def calculate_checksum!
+    def verify
       checksum = model_record.calculate_checksum!
       update_verification_state!(checksum: checksum)
     rescue => e

ee/app/workers/geo/verification_worker.rb

@@ -14,7 +14,7 @@ module Geo
     def perform(replicable_name, replicable_id)
       replicator = ::Gitlab::Geo::Replicator.for_replicable_params(replicable_name: replicable_name, replicable_id: replicable_id)
 
-      replicator.calculate_checksum!
+      replicator.verify
     rescue ActiveRecord::RecordNotFound
       log_error("Couldn't find the record, skipping", replicable_name: replicable_name, replicable_id: replicable_id)
     end

ee/spec/support/shared_examples/models/concerns/verifiable_replicator_shared_examples.rb

@@ -48,7 +48,7 @@ RSpec.shared_examples 'a verifiable replicator' do
     end
   end
 
-  describe '#calculate_checksum!' do
+  describe '#verify' do
     before do
       model_record.save!
     end
@@ -56,7 +56,7 @@ RSpec.shared_examples 'a verifiable replicator' do
     it 'calculates the checksum' do
       expect(model_record).to receive(:calculate_checksum!).and_return('abc123')
 
-      replicator.calculate_checksum!
+      replicator.verify
 
       expect(model_record.reload.verification_checksum).to eq('abc123')
       expect(model_record.verified_at).not_to be_nil
@@ -67,7 +67,7 @@ RSpec.shared_examples 'a verifiable replicator' do
         raise StandardError.new('Failure to calculate checksum')
       end
 
-      replicator.calculate_checksum!
+      replicator.verify
 
       expect(model_record.reload.verification_failure).to eq 'Failure to calculate checksum'
       expect(model_record.verification_retry_count).to be 1

ee/spec/workers/geo/verification_worker_spec.rb

@@ -9,11 +9,11 @@ RSpec.describe Geo::VerificationWorker, :geo do
   let(:job_args) { ['package_file', package_file.id] }
 
   describe '#perform' do
-    it 'calls calculate_checksum!' do
+    it 'calls verify' do
       replicator = double(:replicator)
       allow(::Gitlab::Geo::Replicator).to receive(:for_replicable_params).with(replicable_name: 'package_file', replicable_id: package_file.id).and_return(replicator)
 
-      expect(replicator).to receive(:calculate_checksum!)
+      expect(replicator).to receive(:verify)
 
       described_class.new.perform(*job_args)
     end