"Split brain TXT record expired the time threshold: (0s)" when `gslb` CR gets recreated

[somaritane]

When gslb CR is deleted and then gets recreated, following errors appear in the logs:

k8gb-b6c9b97d6-vqjfm k8gb 2021-02-23T14:58:24.934Z	ERROR	controllers.Gslb	Got the error from TXT based checkAlive. External cluster (test-gslb-failover-tls-heartbeat-sdc.bcp.absa.co.za) doesn't look alive, filtering it out from delegated zone configuration...	{"error": "Split brain TXT record expired the time threshold: (0s)"}

Apparently this happens because depresolver fills predefined values only once per unique gslb spec, and doesn't cater with situation when gslb CR gets re-created by user
https://github.com/AbsaOSS/k8gb/blob/master/controllers/depresolver/depresolver_spec.go#L18

Current workaround is to restart k8gb controller pod, so it rereads gslb CRs and fills missing fields with default values.