fix: remove pollOnce from NativeToJsMessageQueue.popAndEncodeAsJs

[erisu]

Motivation and Context

Remove the require block for cordova/plugin/android/polling, a module that doesn't exist.

Resolves #1735

Description

The cordova/plugin/android/polling module appears to have been removed since 2012.

The last known version of Cordova-JS where this module existed was [email protected] - polling.js in the polling.js file, with the version tag created on Sep 13, 2012.

The module was removed in [email protected], a tag/release created on Oct 16, 2012.

The exact commit that removed the module from Cordova-JS does not have an associated PR, GitHub issue, or CB ticket to explain the reason for this change.

Additionally, the platform-specific Cordova-JS modules, which reside in the cordova-js-src directory of this repository (originally labeled as platform_modules), were not created until 2015—2 years and 4 months later. This directory has also never contained the polling module as far as I can see.

Since this part of the code has not been functional since 2012, I believe it is safe to remove it.

Testing

n/a

Checklist

• [ ] I've run the tests to see all new and existing tests pass
• [ ] I added automated test coverage as appropriate for this change
• [ ] Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• [x] If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• [ ] I've updated the documentation if necessary