This is not allowed for mirror pods

We just mount a path from the host instead.

- change names from `etcd-<role>-0` to `etcd-bootstrap-<role>` to make
  it more clear when `kubectl get pod`
- use the same data directory that etcd managed by etcd-druid would use
  later (it shall just take over the existing data dir)

- With gardener@f9f6a46
  (part of gardener#11853) we only
  skipped static pods during the bootstrap phase. However, we actually
  never want GRM webhooks to react on static pod creations, even if we
  are beyond the bootstrap phase. Otherwise, the kubelet might fail to
  create mirror pods for control plane components if the GRM webhook is
  unavailable. This can lead to undesired behaviour.

- Otherwise, we might get issues when etcd-druid takes over etcd
  management later
- Review this commit with `git diff -w` (ignoring whitespaces)
- `yq` seems to enforce indentation, so let's live with it

Output:

$ go generate ./imagevector/imagevector.go
containers.go
Cloning etcd-druid...
Found etcd-wrapper tag: v0.4.4
Cloning etcd-wrapper at tag v0.4.4...
Found etcd version string: v0.0.0-20240911181550-c123b3ea3db3
Extracted commit hash: c123b3ea3db3
Cloning etcd repo to resolve tag...
Resolved etcd tag: v3.4.34
Updating containers.yaml with etcd v3.4.34 tag
charts.go