Resolve "Clean Up Istio Enabled Logic"

Package Merge Request

Package Changes

Implement a variable and reference that variable to check if istio is enabled. This cleans up the logic checks all throughout the code.

Identified an issue with ELK and Jaeger -- Issue written here: big-bang/product/packages/jaeger#162

No major logic breakage from what I can see. A few helm tests have issues with all packages kicking off, but doesn't seem related to these changes.

All packages installed in a local cluster ( with test-values.yaml) :

For Issue

Closes #2713 (closed)

Closes #2724 (closed)

Upgrade Notices

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