[CI-only] Dev tag update for 1.12.x

[mdeggies]

Description

Pushing per-commit dev images to the hashicorppreview dockerhub org was introduced in #13084, but the tag names have been unclear.

This PR has been created to follow the guidance outlined in https://docs.google.com/document/d/1ovhf8DmlXbsuc45HkN7LdsrS2J3evfSvcy2LPiyUgZ8/edit for dev image naming, and for keeping the version string in version.go up to date. There are two parts to this:

1. Keeping the version strings in version.go on each active release branch, and on main, updated after a release to point to the next minor or major version string. For example, after releasing consul 1.11.6 from branch release/1.11.x, the version string in version.go on release/1.11.x should be updated to 1.11.7.
2. dev_tags, the set of tags that are created for per-commit docker image builds, will be stripped of the patch version. For example, on release/1.11.x, the dev_tags that will be published off of this release branch will be named hashicorppreview/consul:1.11-dev and hashicorppreview/consul:1.11-dev-$COMMITSHA. hashicorppreview/consul:1.11-dev will be kept up to date with the latest builds from branch release/1.11.x.

Testing & Reproduction steps

Dev tags published on this release branch will be named in the following format: hashicorppreview/consul:1.12-dev, hashicorppreview/consul:1.12-$COMMITSHA-dev. See https://hub.docker.com/r/hashicorppreview/consul/tags?page=1&name=1.12-dev to pull the dev image built from commit bfd0dcc from this PR.

Other PR's in this series

Changes to target release/1.11.x: #13539
Changes to target main: #13541

[mdeggies]

This was reviewed over in #13541, so I'm going to merge.