Reduce the amount of time we spend running gh workflows

[richard-cox]

Summary

Reduce the amount of time we spend running gh workflows

Occurred changes and/or fixed issues

• We have a matrix job that splits out e2e tests into multiple jobs
• Previously each job had a step to build the UI.
• Now there's a dependent job that builds the ui and shares it to the matrix job
• If all e2e tests pass first time this adds a smidge of time on to the total (see further optimisations) BUT it reduces the amount of time we consume workers by about 15 x 5 minutes
• If not all e2e tests pass first time it reduces the churn of re-runs by 5 minutes AND the amount of time we consume workers by failed test x 5 minutes
• Further optimisations
  • Total time could be reduced by only installing cypress deps when running matrix step. this at the moment contains all deps to build the ui ... which now doesn't happen there
  • We could also look at pulling & sharing the rancher image in a pre-job, though i'm not sure if this would help that much (1 x image pull from docker vs 1 x image pull from gh)
  • The retention for the build artefacts has been set to 10 days. We can lower this to something like a day. If the artefact is removed the e2e workflow just needs to be re-run again, or just the build step

Technical notes summary

• This is not meant to replace the need for more runners, only to assist until we do

Areas which could experience regressions

• Running code from rancher image and not from build (though tested and this doesn't happen)

Screenshots

Before

After

Checklist

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[nwmac]

LGTM