Add scaling policy type

Raftutil cleanup, plus helper function to find raft.db

* Fix links to ACL guides
* Managing Nomad guide links; links in jsx pages
* job updates guide URLS
* node-drain guide URLS
* outage recovery guide links
* fix guide links - sentinel
* fix guide links - namespaces
* fix guide links - quotas
* fix guide links - autopilot
* more guide links.
* more guide links - continued.
* Updating redirects for learn
* Getting Started
* Load Balancing Guides
* update redirects for ui guide
* Consolidate spark redirects to point to GH repo
* operating job update part 1
* finish operating job links; operations guides links.
* finish guide redirects
* coalesce EOL redirects for spark guides.
* one last link
* Checked links and found a few more stray links
* Found more .htmls
* Fixup links for new HC websites
* Post-merge fixups
* linkcheck caught missing ids

Update Vagrant consul/vault deps

drivers/exec: fix DNS resolution in systemd hosts

drivers/docker/driver.go: change default signal for docker driver to SIGTERM?

Host with systemd-resolved have `/etc/resolv.conf` is a symlink
to `/run/systemd/resolve/stub-resolv.conf`. By bind-mounting
/etc/resolv.conf only, the exec container DNS resolution fail very badly.

This change fixes DNS resolution by binding /run/systemd/resolve as
well.

Note that this assumes that the systemd resolver (default to 127.0.0.53) is
accessible within the container. This is the case here because exec
containers share the same network namespace by default.

Jobs with custom network dns configurations are not affected, and Nomad
will continue to use the job dns settings rather than host one.

Update Vagrant setup to use the consul/vault versions used in CI.

Eliminate sources of randomness in the progress deadline test and clarify the
purpose of the test to check for progress deadline updates.

consul: fix validation of task in group-level script-checks

Required to support tests for namespaces and other ENT features.

When defining a script-check in a group-level service, Nomad needs to
know which task is associated with the check so that it can use the
correct task driver to execute the check.

This PR fixes two bugs:
1) validate service.task or service.check.task is configured
2) make service.check.task inherit service.task if it is itself unset

Fixes #8952

Exercises host volume and Docker volume functionality for the `exec` and `docker`
task driver, particularly around mounting locations within the container and
how this can be used with `template`.

Adds a `nomad_acls` flag to our Terraform stack that bootstraps Nomad ACLs via
a `local-exec` provider. There's no way to set the `NOMAD_TOKEN` in the Nomad
TF provider if we're bootstrapping in the same Terraform stack, so instead of
using `resource.nomad_acl_token`, we also bootstrap a wide-open anonymous
policy. The resulting management token is exported as an environment var with
`$(terraform output environment)` and tests that want stricter ACLs will be
able to write them using that token.

This should also provide a basis to do similar work with Consul ACLs in the
future.

drivers/docker: detect arch for default docker plugin infra_image

The 'docker.config.infra_image' would default to an amd64 container.
It is possible to reference the correct image for a platform using
the `runtime.GOARCH` variable, eliminating the need to explicitly set
the `infra_image` on non-amd64 platforms.

Also upgrade to Google's pause container version 3.1 from 3.0, which
includes some enhancements around process management.

Fixes #8926

The areas of the code this test exercised were merged in with the node
drain tests.

Newer EC2 instances are both cheaper and have generally better
performance.

The dnsmasq configuration had a hard-coded interface name, so in order to
accomodate instances with more recent networking that result in so-called
predictable interface names, the dnsmasq configuration needs to be replaced at
runtime with userdata to select the default interface.

We currently have two jobs commented out in ENT because we don't have the test
target configured there. So having the filter attached to one of those jobs
means changes to filters always create a merge conflict.

docs: Update docs platform components

- We previously added these to the client host metrics, but it's useful to have them on all client metrics.
- e.g. so you can exclude draining nodes from charts showing your fleet size.