Code Modernization: Use null coalescing operator in additional isset() ternaries.
These had been missed previously due to additional parentheses around the `isset()` expressions.
Developed in https://github.com/WordPress/wordpress-develop/pull/10704
Follow-up to [61463], [61457], [61456], [61455], [61454], [61453], [61445], [61444], [61443], [61442], [61436], [61435], [61434], [61403], [61433], [61432], [61431], [61430], [61429], [61424], [61404], [61403].
Props soean.
See #58874, #63430.
Built from https://develop.svn.wordpress.org/trunk@61464
git-svn-id: http://core.svn.wordpress.org/trunk@60776 1a063a9b-81f0-0310-95a4-ce76da25c4cd