Parametrize over tag the docker image name definition

[paolino]

Why

Logs from a pipeline push-to-docker step

2025-01-10 11:26:41 WEST	+ docker load -i artifacts/cardano-wallet-v2025-01-10-test-docker-image.tgz
2025-01-10 11:26:46 WEST	Loaded image: cardanofoundation/cardano-wallet:2025.1.10.1
2025-01-10 11:26:46 WEST	+ echo cardanofoundation/cardano-wallet:test
2025-01-10 11:26:46 WEST	cardanofoundation/cardano-wallet:test

In this case above a release pipeline was triggered by a not-master branch, which implies a (safe) pipeline test, which should push around "stuff" tagged as test, but the image loaded was not tagged as test.

The current docker build step creates image tags based solely on the cabal version of something. In the example above the cabal version was 2025.1.10.1 (the 1 is the test flag), so is the image name. As the wallet cabal version cannot have a test in it so we use arbitrary a 1 at the end of the version number.

OTOH we don't want the dockerhub repository to receive a 2025.1.10.1 image, because it would look like a legit image to download and use (that's why use test as a red flag for test artifacts).

What

Mess up the docker build script to use a TAG variable as the produced image tag and fix the pipeline to pass the TAG on image creation

Acceptance

The log above would become

2025-01-10 11:26:41 WEST	+ docker load -i artifacts/cardano-wallet-v2025-01-10-test-docker-image.tgz
2025-01-10 11:26:46 WEST	Loaded image: cardanofoundation/cardano-wallet:test
2025-01-10 11:26:46 WEST	+ echo cardanofoundation/cardano-wallet:test
2025-01-10 11:26:46 WEST	cardanofoundation/cardano-wallet:test