Fix ejs tests for 3.9 (#44163)
Fix ejs tests for 3.9 (#44163)

TS 3.9 forbids deleting a property that isn't marked optional or
undefined. ejs deletes `delimiter` after setting it, even though it
doesn't have undefined in its type. I couldn't find an example of such
usage, so I deleted the test.

Adding undefined to the type might be the right change, though.
mcliment/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped