Backport of added imagePullPolicy for images in values.yaml into release/1.1.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #2310 to be assessed for backporting due to the inclusion of the label backport/1.1.x.

🚨

Warning automatic cherry-pick of commits failed. If the first commit failed,
you will see a blank no-op commit below. If at least one commit succeeded, you
will see the cherry-picked commits up to, not including, the commit where
the merge conflict occurred.

The person who merged in the original PR is:
@aahel
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/consul-k8s/merges: 409 Merge conflict []

The below text is copied from the body of the original PR.

---

Changes proposed in this PR:

• Added support for a global imagePullPolicy that would be used in all images which are configurable using the helm template.

How I've tested this PR:
rendered helm template and test by passing different values of imagePullPolicy
How I expect reviewers to test this PR:
eg:-
cd charts/consul
helm template
-s templates/api-gateway-controller-deployment.yaml
--set 'apiGateway.enabled=true'
--set 'global.imagePullPolicy="Always"'
--set 'apiGateway.image=bar'
--set 'global.enableConsulNamespaces=true'
. | tee /dev/stderr

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

---

Overview of commits

• 873a317 - 7d233ec - 7f968dc - 50ff429 - 2e0e33c - 5b418e1 - 31e23ad - 473a18b - a4c9d96 - 6e4e1b8 - ca9b271

[hashicorp-cla]

Thank you for your submission! We require that all contributors sign our Contributor License Agreement ("CLA") before we can accept the contribution. Read and sign the agreement

Learn more about why HashiCorp requires a CLA and what the CLA includes

---

1 out of 2 committers have signed the CLA.

• aahel
• temp

---

temp seems not to be a GitHub user.
You need a GitHub account to be able to sign the CLA. If you already have a GitHub account, please add the email address used for this commit to your account.

_{Have you signed the CLA already but the status is still pending? Recheck it.}