Build tag configuration duplicated in many places

[clokep]

Currently the build tags get duplicated in a handful of places:

• Complement CI in GHA
• ~~Complement CI in Buildkite~~
• Synapse CI in GHA
• Synapse complement.sh script
• ~~Synapse CI in Buildkite (which is actually unused, but still sometimes kept in sync)~~
• Dendrite CI in Buildkite

Note that the build tags are homeserver specific (and might vary based on the version of the homeserver).

It would be great if complement was able to know which build tags to use somehow by inspecting a file or the homeserver capabilities. This would help avoid the various configs above getting out of sync.

Additionally we should probably:

• Remove the buildkite CI for complement.
• Remove the unused pipeline for Synapse.

[clokep]

Remove the unused pipeline for Synapse.

See matrix-org/pipelines#170.

[kegsay]

You've done a lot of work on this from what I can see - at what point would you say that this issue is complete?

[clokep]

You've done a lot of work on this from what I can see - at what point would you say that this issue is complete?

I think the main pain point still exists -- you need to specify the attributes in CI for both Synapse, Complement and locally for the complement.sh script. So this is no-where near done.

[kegsay]

What is the state of this @clokep over a year later?