RANGER-5710: Default access audit store to Solr

[ramackri]

Summary

The ClassCastException on multi-value requestUser occurred because installs fell through to the deprecated DB audit path when ranger.audit.source.type was unset or misconfigured:

1. RangerBizUtil defaulted to AUDIT_STORE_RDBMS when the property was missing
2. Docker Postgres install.properties had audit_store=opensearch active while Solr URLs were commented out

This PR fixes configuration defaults so fresh installs and docker stacks use Solr (or explicitly configured OpenSearch), not the legacy DB path.

Changes

• RangerBizUtil: default auditDBType → AUDIT_STORE_SOLR (was AUDIT_STORE_RDBMS)
• conf.dist/ranger-admin-site.xml: default ranger.audit.source.type → solr (was db)
• Docker Postgres install.properties: enable audit_store=solr with FQDN Solr URLs; comment out OpenSearch block

Test plan

• Fresh install: ranger.audit.source.type=solr in ranger-admin-site.xml after setup
• Docker Postgres stack: Admin audit UI queries Solr (no DB path in logs)
• GET /service/assets/accessAudit?requestUser=admin&requestUser=hive → HTTP 200 via Solr path
• Existing installs with explicit ranger.audit.source.type unchanged

https://issues.apache.org/jira/browse/RANGER-5710

[vperiasamy]

LGTM

[mneethiraj]

@ramackri - Ranger doesn't support RDBMS as access audit log store since 2.2.0 release (see RANGER-3184), so this code path is a surprise! This code path was taken due to couple of things:

1. Configuration ranger.audit.source.type is not set in ranger-admin-site.xml
2. Default store is still RDBMS (see the following code block)

class RangerBizUtil {
    String auditDBType = AUDIT_STORE_RDBMS;

   ...
}

Couple of fixes to address this issue:

1. Make sure ranger-admin-site.xml in docker setup is set to solr or opensearch
2. Change the default in RangerBizUtil to AUDIT_STORE_SOLR.

[ramackri]

Thanks @mneethiraj — agreed. RDBMS access audit has been deprecated since RANGER-3184; fixing the STR_LIST cast on XAccessAuditService was treating a symptom on a path we should not hit.

Updated this PR to your suggested fixes:

1. RangerBizUtil: default auditDBType is now AUDIT_STORE_SOLR (was AUDIT_STORE_RDBMS)
2. conf.dist/ranger-admin-site.xml: default ranger.audit.source.type is now solr (was db)
3. Docker Postgres install.properties: audit_store=solr with FQDN Solr URLs enabled; OpenSearch block commented out

Removed the XAccessAuditService STR_LIST change — with Solr as the default, RC1/docker validation should use the Solr path (AccessAuditsService, which already declares requestUser as STR_LIST).