fix: prevent expanding dynamic blocks injecting more than once

[hugorut]

Resolves issue where dynamic blocks add duplicate expanded blocks into the childBlocks of the parent module. For example:

Take the following root module definition:

data "bad_state" "bad" {}

module "reload" {
  source         = "./baz"
  input = [
    {
      "ip"        = "10.0.0.0"
      "mock" = data.bad_state.bad.my_bad["10.0.0.0/24"].id
    },
    {
      "ip"        = "10.0.1.0"
      "mock" = data.bad_state.bad.my_bad["10.0.0.0/24"].id
    }
  ]
}

which calls out to a module with the following terraform:

variable "input" {}

resource "dynamic" "resource" {
  dynamic "child_block" {
    for_each = {
    	for i in var.input : i.ip => i
    }

    content {
      bar = child_block.value.mock
      foo = child_block.value.ip
    }
  }
}

Prior to this change the length of child_block would be 4 instead of the expected 2. This is because on first evaluation data.bad_state.bad.my_bad["10.0.0.0/24"].id is null and then on second evaluation we mock it. This means that we "reload" the underlying module baz which expands the child_block again. The second expansion simply injects two more blocks into childBlocks without clearing the prior expanded blocks.

We now RemoveBlocks of all type before InjectBlock so any prior expanded blocks will be overwritten.

[hugorut]

Ignore google test errors, they are unrelated and due to a regression introduced in the terraform-google-provider: hashicorp/terraform-provider-google#13731