fix(*) remove circular dependency on the Istio submodule

[jpeach]

Summary

The Istio submodule imports Kuma config definitions, and Kuma calls
functions from the Istio submodule. Break the circular dependency by
moving the config definitions into the Istio submodule, even though
they more properly belong in Kuma itself.

This makes it possible to run go mod tidy in the Istio submodule.

Full changelog

N/A

Issues resolved

Fix #2087.

Documentation

N/A

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[jpeach]

Looks like go mod tidy changed the version of Istio that we import. I didn't verify exactly what it did yet.

[jpeach]

Looks like go mod tidy changed the version of Istio that we import. I didn't verify exactly what it did yet.

I see, this is just a dependency on istio.io/pkg, since toe tooling narrowed the set of packages we depend on.

[codecov-commenter]

Codecov Report

Merging #2742 (eaebb0b) into master (56881c1) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2742      +/-   ##
==========================================
+ Coverage   51.75%   51.78%   +0.03%     
==========================================
  Files         869      869              
  Lines       50649    50649              
==========================================
+ Hits        26211    26228      +17     
+ Misses      22351    22324      -27     
- Partials     2087     2097      +10     

Impacted Files	Coverage Δ
pkg/transparentproxy/istio/istio.go	90.90% <100.00%> (ø)
app/kumactl/cmd/root.go	70.17% <0.00%> (-3.51%)	⬇️
pkg/xds/generator/direct_access_proxy_generator.go	83.90% <0.00%> (+1.14%)	⬆️
pkg/core/resources/model/rest/resource.go	69.23% <0.00%> (+1.28%)	⬆️
pkg/insights/resyncer.go	65.67% <0.00%> (+1.49%)	⬆️
pkg/core/resources/manager/cache.go	81.81% <0.00%> (+2.59%)	⬆️
pkg/events/eventbus.go	92.59% <0.00%> (+7.40%)	⬆️
pkg/core/bootstrap/autoconfig.go	54.46% <0.00%> (+8.03%)	⬆️

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