Add leader election configuration to operator deployment

[yuyue9284]

Description

Add config to operator's leader election, for single replica, disable the leader election can prevent the unwanted crash of gpu-operator due to transient error.

#772

Checklist

• No secrets, sensitive information, or unrelated changes
• Lint checks passing (make lint)
• Generated assets in-sync (make validate-generated-assets)
• Go mod artifacts in-sync (make validate-modules)
• Test cases are added for new code paths

Testing

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