[1.17] fix: gwp does not respect image variant

[davidjumani]

Description

Backport of #10603

Ensures the images generated in the gatewayparams via helm respect the global.image.variant

Context

https://github.com/solo-io/solo-projects/issues/7803

Testing steps

Before :

helm-template-oss --set kubeGateway.enabled=true --set global.image.variant=fips-distroless

# Source: gloo/templates/43-gatewayparameters.yaml
kind: GatewayParameters
...
    sdsContainer:
      image:
        registry: quay.io/solo-io
        repository: sds-ee
        tag: 1.0.0-ci1

After :

helm-template-oss --set kubeGateway.enabled=true --set global.image.variant=fips-distroless

# Source: gloo/templates/43-gatewayparameters.yaml
kind: GatewayParameters
...
    sdsContainer:
      image:
        registry: quay.io/solo-io
        repository: sds-ee-fips
        tag: 1.0.0-ci1-distroless

Notes for reviewers

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

[solo-changelog-bot]

Issues linked to changelog:
https://github.com/solo-io/gloo/issues/10602