fleet: Allow increasing the fleet replicas during a rolling update

[GonzaloSaez]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking
/kind bug
/kind cleanup
/kind documentation

/kind feature

/kind hotfix
/kind release

What this PR does / Why we need it:

Addresses #3970 by adding an extra boolean option to the fleet strategy that allows scaling up the replica count based on the RollingUpdate settings when patching the fleet config. This allows fleets to behave a bit more like a Deployment when there is a redeployment. The new feature unblocks fleets that have all their replicas in Allocated state at the same time that a fleet update is requested. Previously, the new GameServerSet would get stuck until one of the fleet's GameServer was deleted/brought back to Ready state.

Which issue(s) this PR fixes:

Closes #3970

Special notes for your reviewer:

I'm not sure if this is a feature that the Agones maintainer want to support moving forward. This feature is useful for some of my use cases and it'd be difficult for me to maintain it ouside this repo. Happy to hear the opinions of others regarding this new functionality.

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[agones-bot]

Build Failed 😭

Build Id: 5b824c81-d928-421c-a81a-0d1977863049

Status: FAILURE

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[agones-bot]

Build Failed 😭

Build Id: 64243212-5c9f-4cdf-bc35-27cd5a566d28

Status: FAILURE

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[gongmax]

Do you think #3762 fixes your use case?

[markmandel]

This PR hasn't been updated since September -- I'm thinking we close this.

@igooch , @gongmax, @GonzaloSaez any objections?

[GonzaloSaez]

This PR hasn't been updated since September -- I'm thinking we close this.

@markmandel I'm okay with closing this but I still think we should still fix the issue linked to this PR since it disallows rolling updates if the fleet is full.

[markmandel]

@GonzaloSaez you never said if RollingUpdateFix fixed your issue or not?

[GonzaloSaez]

@GonzaloSaez you never said if RollingUpdateFix fixed your issue or not?

Sorry I forgot to answer that one. I don't think that RollingUpdateFix address the issue I describe. The problem that I describe is that there is no way to rollout new replicas if we are at capacity and we want to add more GameServer to our fleet.