feat(api): remove golang experimental packages [EE-3648] (#8081)

* remove golang experimental packages

* rebase and fix references

api/internal/slices/slices.go

@@ -0,0 +1,22 @@
+package slices
+
+// Contains is a generic function that returns true if the element is contained within the slice
+func Contains[T comparable](elems []T, v T) bool {
+	for _, s := range elems {
+		if v == s {
+			return true
+		}
+	}
+	return false
+}
+
+// IndexFunc returns the first index i satisfying f(s[i]),
+// or -1 if none do.
+func IndexFunc[E any](s []E, f func(E) bool) int {
+	for i, v := range s {
+		if f(v) {
+			return i
+		}
+	}
+	return -1
+}