[TT-13615] Add imageRegistry

[zalbiraw]

Description

As a user I would like to set the imageRegistry for all my containers

This removes docker.tyk.io from gateway and pump containers. It can readded as if statement but I dont know if we track this anymore. Maybe there should be a different way to track things.

This feature is required for enterprise deployments where the users have their own registry.

Changes ported to operator chart
https://github.com/TykTechnologies/tyk-operator-internal/pull/98

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Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)
• Documentation updates or improvements.

Checklist

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• My change requires a change to the documentation.
  • I have manually updated the README(s)/documentation accordingly.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.