fix: delete istio resources when istio is disabled, fixes RHOAIENG-5158

[dhirajsb]

Description

When istio config is missing, delete all istio resources Fixes RHOAIENG-5158

How Has This Been Tested?

Merge criteria:

• [x] The commits and have meaningful messages; the author will squash them after approval or will ask to merge with squash.
• [x] Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• [x] The developer has manually tested the changes and verified that the changes work