s3: includes: Make the comments describing itime consistent. Always use "invented...

s3: includes: Make the comments describing itime consistent. Always use "invented" time.

It gets confusing if we call it "imaginary" or "instantiation"
in different places.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14928

Signed-off-by: Jones Syue <jonessyue@qnap.com>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Mon Jan 10 18:42:02 UTC 2022 on sn-devel-184

(cherry picked from commit 745af26a1a6531b2e906aa7c1c0355cbab658441)

Autobuild-User(v4-14-test): Jule Anger <janger@samba.org>
Autobuild-Date(v4-14-test): Wed Jan 12 12:26:56 UTC 2022 on sn-devel-184