[bitnami/redis] Fix issues in initialization/restarts

[rafariossaa]

Description of the change

I noticed kubernetes DNS issues when running the chart, and also sentinels did not clean its sentinels list of nodes.

The DNS issues consists in that starting node IP take a while to be added to the headless service DNS entry, so a wait was added to ensure that DNS content is reliable.
On sentinel nodes list issu, when a node is restarted it is added to the sentinel list, but the old one is not cleaned. This lead to sentinels think that they are more nodes than the actually existing hence there won't be quorum to elect a new master if needed.

Benefits

This should fix starting issues that lied to having more than one master and issues where a master was not promoted.

Possible drawbacks

Applicable issues

• fixes Redis sentinel is not picking right master after master pod restart #3700, [bitnami/redis] After failover+recover, there will be two masters (with simple reproducible experiments) #3202, [bitnami/redis] all redis/sentinel pods become master at initial install #5347, Redis: Error condition on socket for SYNC: No route to host #5164, redis + sentinel master pod reschedule / deletion results in two masters #5543, [bitnami/redis] All pods in CrashLoopBackOff status after rebooting worker nodes #5181, No route to host error after Redis master re-spawned #1544

Additional information

Checklist

• Chart version bumped in Chart.yaml according to semver.
• Variables are documented in the README.md
• Title of the PR starts with chart name (e.g. [bitnami/chart])

⚠️ Keep in mind that if you want to make changes to the kubeapps chart, please implement them in the kubeapps repository. This is only a synchronized mirror.

[juan131]

LGTM

[rafariossaa]

Thanks !
I am merging it.