Update Helm release velero to v2.27.0

See merge request stackspin/stackspin!654

fix cert-manager-override

See merge request stackspin/stackspin!660

Resolve "Fix ZeroSSL configuration"

Closes #1059

See merge request stackspin/stackspin!648

Resolve "Remove Rocketchat"

Closes #1049

See merge request stackspin/stackspin!656

Closes: #1049

Close: #1059

Resolve "Revisit flux dependencies"

Closes #1042

See merge request stackspin/stackspin!653

Resolve "Reduce kustomization healthCheck timeouts"

Closes #1055

See merge request !652

first commit to move everything to its own kustomization, also removes deprecated value from kustomizations

Resolve "Update flux"

Closes #1048

See merge request stackspin/stackspin!634

set timeouts for all Flux kustomizations to 20m instead of the default (which is the same as its interval)

Update dependency kubernetes to v20

See merge request stackspin/stackspin!651

Update Helm release metallb to v2.5.13

See merge request stackspin/stackspin!650

Update Helm release ingress-nginx to v4.0.12

See merge request stackspin/stackspin!649

We need helm 3.7 because some charts we use make use of a helm 3.7 feature
(subchart values).
See stackspin/stackspin#1048 for more
details.

Closes: #1048