refactor: Remove unused api/variables package (#623)

**What problem does this PR solve?**:
Removes code that appears to be unused.

**Which issue(s) this PR fixes**:
Fixes #

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Author: dlipovetsky

api/go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/nutanix-cloud-native/prism-go-client v0.4.0
 	github.com/onsi/gomega v1.33.1
 	k8s.io/api v0.29.3
-	k8s.io/apiextensions-apiserver v0.29.3
 	k8s.io/apimachinery v0.29.3
 	k8s.io/utils v0.0.0-20231127182322-b307cd553661
 	sigs.k8s.io/cluster-api v1.7.1
@@ -70,6 +69,7 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/apiextensions-apiserver v0.29.3 // indirect
 	k8s.io/client-go v0.29.3 // indirect
 	k8s.io/component-base v0.29.3 // indirect
 	k8s.io/klog/v2 v2.120.1 // indirect