Don't check ILM policies on 8.15+

[vikmik]

Since we don't use ILM policies anymore on 8.15+, I made the test conditional on the version.

Tested with with:

make smoketest/run-version TEST_DIR=./testing/smoke/basic-upgrade SMOKETEST_VERSION=latest

[mergify]

This pull request does not have a backport label. Could you fix it @vikmik? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-7.17 is the label to automatically backport to the 7.17 branch.
• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.

NOTE: backport-skip has been added to this pull request.