ci: add empty CODEOWNERS file

Add an empty codeowner file redirecting to MAINTAINERSS.yml file for
clarity and to make some tooling happy.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

CODEOWNERS

@@ -0,0 +1,4 @@
+# Instead of the CODEOWNERS file, The Zephyr Project uses a custom format.
+# See MAINTAINERS.yml for details.
+#
+# DO NOT EDIT THIS FILE.

scripts/ci/twister_ignore.txt

@@ -25,6 +25,7 @@
 .github/workflows/issues-report-config.json
 .github/workflows/backport_issue_check.yml
 MAINTAINERS.yml
+CODEOWNERS
 LICENSE
 Makefile
 doc/*