fix(#9604): fix integer validation in sms rules (backport)

[garethbowen]

Description

Code review checklist

• [ ] Readable: Concise, well named, follows the style guide, documented if necessary.
• [ ] Documented: Configuration and user documentation on cht-docs
• [ ] Tested: Unit and/or e2e where appropriate
• [ ] Internationalised: All user facing text
• [ ] Backwards compatible: Works with existing data and configuration or includes a migration. Any breaking changes documented in the release notes.

Compose URLs

If Build CI hasn't passed, these may 404:

• Core
• CouchDB Single
• CouchDB Cluster

License

The software is provided under AGPL-3.0. Contributions to this project are accepted under the same license.

[garethbowen]

@dianabarsan Would you mind also reviewing this one? It's a custom backport because master has further changes which conflicted and I didn't want to destabalise 4.14.x more than necessary.