covered primary scan on system:<keyspaces> is not working

MB-19443. Optimize WHERE FALSE, WHERE TRUE, and SELECT META().id ..

After above fix select meta().id from system:<keyspaces> will not work because
when where clause is missing or evaluate true. It uses PrimaryCoveringScan with predicatee where meta().id is not null.
ScanEntries we may have to meta attachment to Annotated value like execution/scan_index.go

Example
"select meta().id from system:prepareds;” ===> "select meta().id from system:prepareds where meta().id is not null;”