review cas-backend validation on-boot

[migmartri]

I've noticed that the controlplane takes more time to boot and I can see all these entries in the logs. Are we performing validations synchronously by any chance?

level":"info","ts":1762293966.5488975,"kind":"server","component":"http","operation":"/controlplane.v1.StatusService/Statusz","args":"readiness:true","code":0,"reason":"","stack":"","latency":0.018403929}
{"level":"info","ts":1762293967.6216676,"component":"biz/CASBackend","msg":"validation OK","ID":"83f60f49-9525-4fa8-ab0f-8054ada41aac"}
{"level":"info","ts":1762293967.621702,"component":"biz/CASBackend","msg":"updating validation status","ID":"83f60f49-9525-4fa8-ab0f-8054ada41aac","status":"OK","error":null}
{"level":"info","ts":1762293967.7486613,"component":"biz/CASBackend","msg":"validation OK","ID":"2968e907-0864-49f5-9b79-a065c84e4bde"}
{"level":"info","ts":1762293967.748708,"component":"biz/CASBackend","msg":"updating validation status","ID":"2968e907-0864-49f5-9b79-a065c84e4bde","status":"OK","error":null}
{"level":"info","ts":1762293967.8450963,"component":"biz/CASBackend","msg":"validation OK","ID":"e0867f00-c92e-4129-af54-07986ba5ab92"}
{"level":"info","ts":1762293967.8451402,"component":"biz/CASBackend","msg":"updating validation status","ID":"e0867f00-c92e-4129-af54-07986ba5ab92","status":"OK","error":null}
{"level":"info","ts":1762293967.952144,"component":"biz/CASBackend","msg":"validation OK","ID":"6fc257fb-8f9b-4f76-973d-c012b0b7b23d"}
{"level":"info","ts":1762293967.9521835,"component":"biz/CASBackend","msg":"updating validation status","ID":"6fc257fb-8f9b-4f76-973d-c012b0b7b23d","status":"OK","error":null}
{"level":"info","ts":1762293968.0765147,"component":"biz/CASBackend","msg":"validation OK","ID":"6c5db18b-c649-4cbc-be65-781667dacdb9"}
{"level":"info","ts":1762293968.0765536,"component":"biz/CASBackend","msg":"updating validation status","ID":"6c5db18b-c649-4cbc-be65-781667dacdb9","status":"OK","error":null}
{"level":"info","ts":1762293968.1929479,"component":"biz/CASBackend","msg":"validation OK","ID":"5e16ef98-68b6-4fe6-96e2-803c84d182f9"}
{"level":"info","ts":1762293968.1929839,"component":"biz/CASBackend","msg":"updating validation status","ID":"5e16ef98-68b6-4fe6-96e2-803c84d182f9","status":"OK","error":null}

why do we need to validate at boot?

cc/ @javirln @jiparis