Need to re-configure routing after we add a new nodegroup (rack)

[Aleksandr Didenko]

When we have a working env with multiple nodegroups and we add nodes from new rack (new nodegroup), we should re-configure static routes on all nodes in the env.

Steps to reproduce:
1. Deploy multirack evn with 2+ nodegroups
2. Add new nodegroup
3. Add 1+ nodes (computes, for example) from new nodegroup
4. Deploy changes
5. Run OSTF

Expected result:
OSTF passes, there are routes to new nodegroup on all nodes

Actual result
OSTF fails, there are no routes to new nodegroup on old nodes

[Aleksey Kasatkin (alekseyk-ru)]

Fixed with https://review.openstack.org/#/c/250507/

Rerun network setup on deployed nodes
This is required to apply changes that could be made to the networking configuration of environment.
The major case is: add/remove node network group(s).

The configuration changes are not tracked as nailgun does not have proper functionality for that.

New key is introduced in task description: reexecute_on (list). Deployment tasks which are to be re-executed on deploy changes must have

reexecute_on:
    - deploy_changes

DocImpact

Change-Id: I668fcb426826cecf69a5c7fc1e92b8ae8dfeef9f
Blueprint: redeploy-network-on-changes

[Mikhail Samoylov (msamoylov)]

Verification passed in fuel version:
VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "8.0"
  api: "1.0"
  build_number: "414"
  build_id: "414"
  fuel-nailgun_sha: "9ebbaa0473effafa5adee40270da96acf9c7d58a"
  python-fuelclient_sha: "4f234669cfe88a9406f4e438b1e1f74f1ef484a5"
  fuel-agent_sha: "df16d41cd7a9445cf82ad9fd8f0d53824711fcd8"
  fuel-nailgun-agent_sha: "92ebd5ade6fab60897761bfa084aefc320bff246"
  astute_sha: "c7ca63a49216744e0bfdfff5cb527556aad2e2a5"
  fuel-library_sha: "7ef751bdc0e4601310e85b8bf713a62ed4aee305"
  fuel-ostf_sha: "214e794835acc7aa0c1c5de936e93696a90bb57a"
  fuel-mirror_sha: "b62f3cce5321fd570c6589bc2684eab994c3f3f2"
  fuelmenu_sha: "2a0def56276f0fc30fd949605eeefc43e5d7cc6c"
  shotgun_sha: "63645dea384a37dde5c01d4f8905566978e5d906"
  network-checker_sha: "9f0ba4577915ce1e77f5dc9c639a5ef66ca45896"
  fuel-upgrade_sha: "616a7490ec7199f69759e97e42f9b97dfc87e85b"
  fuelmain_sha: "cfeadd34d8d048deeabf0884931708b1d040b8a6"

Verification steps like in bug description