fix: Use kubectl serverside apply instead of kubectl replace to update kube-prometheus-stack CRDs

What does this MR do?

Changes the command for updating kube-prometheus-stack CRDs in existing installations to use kubectl apply --server-side per the kube-prometheus-stack documentation, instead of kubectl replace. Use of kubectl replace was failing on CRDs that had not been previously created in the cluster, although this was only recently revealed with a refactor in !1314 (merged) to run each CRD update in a loop, instead of as a block shell command (because the final update would succeed and therefore the whole step would succeed, even though the non-existent CRDs were failing the whole time).

Also pulled out the namespace scoping on the command because CRDs are non-namespaced.

Related issues

Closes #887 (closed)

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
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