widget-conditions: fix regression introduced in #22414

[yoavf]

Fixes #22460.

This commit syncs r238742-wpcom.

In #22414, a couple of the changes switched to strict equality when the actual data compared had different types.
This meant that if a legacy widget was saved with visibility on a specific page, it would never show on that page (or any other page).
This was documented in Automattic/wp-calypso#60352 and Automattic/wp-calypso#60355

Changes proposed in this Pull Request:

• Fixes regression by casting the page ID data from the visiblity rule to int

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

• Add a legacy widget to a theme with a widget area
• Set the widget to be visible on a specific page
• Update
• Visit that page, widget should be visible

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