K8SPSMDB-961: add `.spec.sharding.balancer.enabled` #3001

Job	Run time
runner / alex	30s
runner / suggester / golangci-lint	3m 20s
runner / suggester / gofmt	7s
runner / misspell	10s
runner / shellcheck	10s
runner / suggester / shfmt	28s
	4m 45s

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