Update envtest version

[aidandunlop]

Is your feature request related to a problem? Please describe.
The decoupled-tests currently rely on env-test, which is pinned to version v0.8.3 in common.mk. This version currently fails on arm based macs with the error:

fetching envtest tools@1.19.2 (into '<path_to_project>/kfp-operator/testbin')
tar: Error opening archive: Unrecognized archive format
make: *** [decoupled-test] Error 1

Describe the solution you'd like
Later versions of env-test work as expected, so we should upgrade the version of env-test. The setup-envtest.sh hack seems to have been dropped in later versions, so we should modify the installation of env-test to be the recommended method, though it's not initial clear what that at first glance.

Describe alternatives you've considered
n/a

Additional context

• Details on using envtest from the kubebuilder book
• Envtest binaries manager

Current workaround

• On an arm based mac, delete any previous copies of the testbin dir
• Attempt to run makefile decoupled-test, this should fail
• Modify the envtest version in ./testbin/setup-envtest.sh to 1.24.1: ENVTEST_K8S_VERSION:-1.24.1
• Rerun makefile decoupled-test

[TobyPinfold]

Taking a look into this, in-order to update the envtest version from 0.8 we will also need to bump the controller-runtime to a newer version. This brings in some enforcement of validation webhooks on custom resources. Given we have already started the process of creating a V1alpha6 api version I would suggest this work is paused until v1alpha6 is available.