Run cross-release SQL integration tests (#403)

* Run cross-release SQL integration tests

Run SQL integration tests across arbitrary schema and server
releases.

Refer to integration/README.md in this change for more information.

TESTED=Cloud build changes tested with cloud-build-local
       Used the published jars to test sqlIntegration task locally.

db/build.gradle

@@ -106,17 +106,18 @@ task compileApiJar(type: Jar) {
 
 configurations {
   compileApi
+  schema
 }
 
 artifacts {
-  archives schemaJar
   compileApi compileApiJar
+  schema schemaJar
 }
 
 publishing {
   repositories {
     maven {
-      url project.schema_publish_repo
+      url project.publish_repo
     }
   }
   publications {