Add updateStrategy to Telegraf Deployment.

[Foosvald]

This makes it possible to configure the updateStrategy for the Telegraf Deployment.

In our use case and clusters we have podAntiAffinity configured for the Telegraf Deployment and to avoid pods being stuck in state Pending we also want to set updateStrategy.type: Recreate.

I've manually tried this change with:

updateStrategy: {}

updateStrategy:
  type: RollingUpdate
  rollingUpdate:
    maxUnavailable: 1
    maxSurge: 1

updateStrategy:
  type: Recreate

Which all correctly set the strategy on the Deployment.

• CHANGELOG.md updated -> Doesn't seem to exist anymore?
• Rebased/mergable
• Tests pass
• Sign CLA (if not already signed)

[alespour]

LGTM

[Foosvald]

Ping @alespour, @popey or @alespour, do you think you could review and hopefully approve this? It would be nice to not have to keep a local fork of the Helm chart for our builds :)

[popey]

@Foosvald sorry, I'm no longer at Influx. Perhaps @powersj can help?

[alespour]

LGTM.