test: Add Negative unit tests

[britaniar]

Description of your changes

Add negative unit tests to TestReconcilerUpdateBindings function.

Fixes #

I have:

• Run make reviewable to ensure this PR is ready for review.

How has this code been tested

Special notes for your reviewer

[Arvindthiru]

There are more negative UTs to be added, there are three branches where,

• The first branch with case fleetv1beta1.BindingStateBound has an Update you can mock to return error
• The second branch with case fleetv1beta1.BindingStateScheduled has another update you can mock to return error
• The third branch with case fleetv1beta1.BindingStateUnscheduled has a Delete which can possibly return a not found error or some other error as well

[Arvindthiru]

LGTM!!