Fix/slack integration

[lindenmckenzie]

What

This began as fixing a slack failure whereby it was sending multiple messages on a failure but has ended up as a larger refactor.

The meat of this is that now rather than managing a job "transition" on task success, we also do it on failure. Additionally, the store will now report back if a state transition has already been done to cut down on race condition / clashes.

Other minor fixes:

• hide slack api token from logs (not currently a security concern as it was not deployed)
• failure messages to info channel now show a red line
• consistent ordering of slack details
• other minor tidy ups (log messages)
• upgrade go to 1.26.1
• refactor CI tests to not use setup

How to review

Check looks ok, makes sense, tests pass.

To optionally test, you can:

• retrieve a slack token from https://api.slack.com/ for the migration service
• set the slack variables in the migration service in dp-compose
• run the test migration to see success
• to see failure, I switched off the dp-upload-service and then ran the test migration

Who can review

Not me.