Update jobs_current_version_uuid_index and jobs_symlink_target_uuid_index to ignore NULL values

Signed-off-by: Michael Collado <collado.mike@gmail.com>

Author: collado-mike

Diff for: api/src/main/resources/marquez/db/migration/V51__job_indices_for_lineage.sql

@@ -1,10 +1,10 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 
 create index jobs_current_version_uuid_index
-    on jobs (current_version_uuid);
+    on jobs (current_version_uuid) WHERE current_version_uuid IS NOT NULL;
 
 create index jobs_symlink_target_uuid_index
-    on jobs (symlink_target_uuid);
+    on jobs (symlink_target_uuid) WHERE symlink_target_uuid IS NOT NULL;
 
 create index jobs_current_job_context_uuid_index
     on jobs (current_job_context_uuid);