fix: add elect-leader flag to the pflag

[aagusuab]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Currently, setting up the autoscaler pod with --elect-leader flags causes
unknown flag: elect-leader error.
The current main function leaves out the elect leader flag from the flag initialization.
This PR will fix that.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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[x13n]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aagusuab, x13n

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