Ensure the err is surfaced in e2e/integration tests to improve debuggability

[mimowo]

What would you like to be cleaned:

We use this pattern in many places :

if err := k8sClient.Get(ctx, wlLookupKey, createdWorkload); err != nil {
return false
}

We prefer to replace it with something like:

gomega.Eventually(func(g gomega.Gomega) {
	g.Expect(k8sClient.Get(ctx, wlLookupKey, createdWorkload)).Should(gomega.Succeed())
	...
}, util.LongTimeout, util.Interval).Should(gomega.Succeed())

This is a follow up to the discussion here: #3284 (comment)

Why is this needed:

To improve debuggability.

[mbobrovskyi]

/assign

I already started working on it before.