fix: name of the FluxInstance has to be "flux"

[budimanjojo]

flux-operator only accept "flux" as the metadata name of FluxInstance

ref: controlplaneio-fluxcd/flux-operator#266

[stefanprodan]

This is not needed because the fullnameOverride is hardcoded in values to flux.

[budimanjojo]

@stefanprodan I reported the issue in the flux-operator repo because I changed fullnameOverride in my values to something else and it broke flux for me. And now that changing the value is not permitted at all in the operator side, it makes sense to disable changing fullnameOverride at all in the charts, isn't it?

[stefanprodan]

It doesn't make sense to me, if we hardcode the name in the FluxInstance then we allow for the release name to be something else, which is wrong. After the next operator version, if you change the fullnameOverride the release will fail to install, telling you the name the wrong.