Spotinst: Attempt to find a Security Group even without a VPC ID

[liranp]

Specifying additional security groups in the InstanceGroup's spec resulted in a spurious change. This happens because of an incorrect value (nil, actually) returns from this function, although there is no reason for it to be done this way since the VPC ID is only used in L115.

This PR eliminates ths spurious change by allowing the find function to be executed even without a VPC ID.

Steps to reproduce

1. Edit the instance group by adding an additional security group:

apiVersion: kops/v1alpha2
kind: InstanceGroup
spec:
  additionalSecurityGroups:
  - sg-<REDACTED#2>

2. Update the cluster. In the logs you'll see thw following change:

Elastigroup/nodes.<cluster_name>
        SecurityGroups           [name:nodes.<cluster_name> id:sg-<REDACTED#1>] -> [name:nodes.<cluster_name> id:sg-<REDACTED#1>, name:sg-<REDACTED#2> id:sg-<REDACTED#2>]

3. Update the cluster once again and you'll see the same output, which is a result of a spurious change.

[KashifSaadat]

The lines removed above were also validating that e.VPC.ID is not null. Was this an invalid case, or do you need to extend your if check here?

[liranp]

@KashifSaadat Thanks! Good catch, fixed.

[KashifSaadat]

Hey @liranp, thanks for the contribution :) Just one small query I added, otherwise the change looks good.

/ok-to-test

[KashifSaadat]

Great, thanks @liranp !

/ok-to-test
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: KashifSaadat, liranp

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