Clean up expired package blobs on k8s

We will never have a package_hash (sha1 checksum) when using a package
registry, but will have a sha256 checksum. We don't expect this change
to negatively effect "legacy" configurations.

[#175080280]

Co-authored-by: Matt Royal <mroyal@pivotal.io>
Co-authored-by: Tim Downey <tdowney@vmware.com>

Author: matt-royal

app/jobs/runtime/expired_blob_cleanup.rb

@@ -9,7 +9,7 @@ def perform
             enqueue_droplet_delete_job(droplet.guid)
           end
 
-          PackageModel.where(state: PackageModel::EXPIRED_STATE).exclude(package_hash: nil).each do |package|
+          PackageModel.where(state: PackageModel::EXPIRED_STATE).exclude(package_hash: nil, sha256_checksum: '').each do |package|
             enqueue_package_delete_job(package.guid)
           end
         end

spec/unit/jobs/runtime/expired_blob_cleanup_spec.rb

@@ -61,9 +61,16 @@ module Jobs::Runtime
             expect(Delayed::Job.last.handler).to include('DeleteExpiredPackageBlob')
           end
 
-          it 'does nothing when package_hash is nil' do
+          it 'enqueues a deletion job when only package_hash is nil' do
             expired_package.update(package_hash: nil)
 
+            expect { job.perform }.to change { Delayed::Job.count }.by(1)
+            expect(Delayed::Job.last.handler).to include('DeleteExpiredPackageBlob')
+          end
+
+          it 'does nothing when both package_hash and sha256_checksum are blank' do
+            expired_package.update(package_hash: nil, sha256_checksum: '')
+
             expect { job.perform }.not_to change { Delayed::Job.count }.from(0)
           end
         end