Description of the Change

This PR fixes the the issue where the Sync interruption messages always show ElasticPress.io regardless of host settings. The issue was when Utils\is_epio() returns 0 , wp_localize_script convert it into string '0' and in JS if ( '0' ) gives true .

With the use of FILTER_VALIDATE_BOOLEAN is_epio returns empty in case of false and 1 if the value is true.

Closes #2784

Verification Process

• Start a delete and sync from the sync page.
• Run wp elasticpress stop-indexing
• Click Show log and review the message.
• The message would have Your indexing process has been stopped by WP-CLI and your Elasticsearch index could be missing content incase of self hosted ElasticSearch

Changelog Entry

Fixed: Sync interruption message always mentions ElasticPress.io

Credits

Props @burhandodhy