[v2.8] Remove doNotRelease tag from Fleet and add Fleet 0.8.0 rc.9

[thardeck]

following the branching strategy guide.

I am using yq version 4 to change the release.yaml that's why the indentation of it is changed a bit.

Sadly `yq` enforces indentation for arrays atm because of this issue: https://github.com/mikefarah/yq/issues/1309
That's why I have to fix the indentation with sed manually after using yq.
Maybe we should enforce `yq` default indentation for the release.yaml in the future so manual fixes are not required.

[rohitsakala]

@thardeck Could you create an issue for yq ? and add team/mapps and next up label so that we can work on it later

[thardeck]

@thardeck Could you create an issue for yq ? and add team/mapps and next up label so that we can work on it later

I have created an issue: https://github.com/rancher/charts/issues/2949