Finalizers added after first read operation on AWS in AWSMachines

[shivi28]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Update finalizer addition logic for AWSMachine. If we apply AWS workload cluster yaml with invalid credentials, then AWSMachine object is created and stuck because of invalid credentials. Once we try to delete that yaml, AWSMachine object stuck. So adding finalizer in AWSMachine only after first successful AWS read operation.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #2270

Special notes for your reviewer:
With this change AWSMachine object is deleted in case of invalid credentials, same needs to be done for AWSCluster. WIP because AWSCluster finalizer updation requires a bit of refactoring in reconciliation logic

Checklist:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

Release note:

AWSMachine objects successfully deleted in case of invalid credentials

[randomvariable]

Need to update the tests appropriately, as the logic has changed.

[randomvariable]

/lgtm
/priority important-soon

/assign @sedefsavas for another set of 👁️ and approval

[sedefsavas]

One problem might be: this does not solve the case where the credentials were valid initially (the first findInstance() call succeeded), then for example it expired.

I don't think there is an easy solution for this.

[randomvariable]

No probably not. I don't think there's much more we can do here without modelling a more complex state machine. It at least unblocks the most trivial use case.

[sedefsavas]

/approve

[k8s-ci-robot]

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