### Description

Currently, when we execute retention policy, we also refresh the destination index by setting:
```
setRefresh(true)
```
on the DBQ request.
This can cause permission errors which are surprising to the user as the permissions are not required when the transform starts:
```
task encountered irrecoverable failure: org.elasticsearch.ElasticsearchSecurityException: action [indices:admin/refresh] is unauthorized for user [found-internal-kibana4-server] with roles [kibana_system,found-internal-kibana4-server] on indices [logs-cloud_security_posture.findings_latest-default], this action is granted by the index privileges [maintenance,manage,all]
```

We still want the user to have the permissions to delete the documents. But we should execute `refresh` as the system user.
x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/RetentionPolicyConfigToDeleteByQueryTests.java
Collections.emptyMap(),
            8_000_000L
        );
        DeleteByQueryRequest deleteByQueryRequest = RetentionPolicyToDeleteByQueryRequestConverter.buildDeleteByQueryRequest(
            retentionPolicyConfig,
            settingsConfig,
            destConfig,
            checkpoint
        );
        assertNotNull(deleteByQueryRequest);
        assertNotNull(deleteByQueryRequest.getSearchRequest().source());
        assertNotNull(deleteByQueryRequest.getSearchRequest().source().query());
        assertTrue(deleteByQueryRequest.isRefresh());
        assertEquals(0, deleteByQueryRequest.getMaxRetries());
        assertEquals(1, deleteByQueryRequest.getSearchRequest().indices().length);
        assertEquals(destConfig.getIndex(), deleteByQueryRequest.getSearchRequest().indices()[0]);
        if (settingsConfig.getDocsPerSecond() != null) {
            assertEquals(settingsConfig.getDocsPerSecond().floatValue(), deleteByQueryRequest.getRequestsPerSecond(), 1E-15);
        }
        QueryBuilder query = deleteByQueryRequest.getSearchRequest().source().query();
        assertThat(query, instanceOf(RangeQueryBuilder.class));
        RangeQueryBuilder rangeQuery = (RangeQueryBuilder) query;
        assertThat(rangeQuery.to(), equalTo(DateFormatter.forPattern("strict_date_optional_time").formatMillis(9_940_000L)));
        assertTrue(rangeQuery.includeLower());
    }
    private static RetentionPolicyConfig randomRetentionPolicyConfig() {
        return TimeRetentionPolicyConfigTests.randomTimeRetentionPolicyConfig();
    }
}