Update consul to version 1.9.6

What does this MR do?

Updates Consul to 1.9.6 to ensure we are on a supported version.

Consul servers must be upgraded one at a time, and gitlab-ctl reconfigure does not issue a restart, so the restart command must be issued manually using gitlab-ctl restart consul on consul daemon nodes.

Related issues

Closes #5908 (closed)

Test plan

• Fresh install works, consul works in a PG-HA setup
• Upgrade works
  • Package upgrade reconfigure notifies user to restart consul
  • Restarting consul works correcltly
  • Reconfigure after a restart no longer shows the message
  • The consul cluster works fine with a mix of our old and new consul servers

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
• trigger-package has a green pipeline running against latest commit

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened