[backport-1.3]: timeout on "Trigger reconciliation of units" / Flux Helm controller OOM

Issue #2131 (closed) needs to be backported to 1.3.x

🗒️ by @tmmorin: The OOM solved by #2131 (closed) has not, to my knowledge, be observed on Sylva 1.3 deployments. However it triggers right at the step where we upgrade to Sylva main (when we update the sylva-units HelmRelease). So to prevent this we need to give more memory to the Flux Helm controller before this, i.e. in Sylva 1.3.