Wrapper/package istio injection fix

Package Merge Request

Package Changes

Modifies the istio injection value to be a string for "enabled" or "disabled" to align with how other packages have this. Also passes this down to the wrapper in the same way, and has modifications to the wrapper to ensure that is interpreted properly.

Package MR

big-bang/product/packages/wrapper!7 (merged)

For Issue

Closes #1475 (closed)