K8SPG-703: add `internal.percona.com/keep-job` finalizer for backups #4215

Job	Run time
runner / suggester / goimports-reviser	27s
runner / alex	39s
runner / suggester / gofmt	8s
runner / manifests	1m 32s
runner / suggester / golangci-lint	2m 54s
runner / shellcheck	5s
runner / misspell	16s
runner / suggester / shfmt	26s
	6m 27s

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