[Streams] Make root stream selectively immutable

[Kerry350]

Summary

This closes https://github.com/elastic/streams-program/issues/54.

The root stream is selectively immutable (processing and fields changes are not allowed).

UI

For the UI I've entirely disabled the actions column for the root stream in the schema editor. All of the information (bar the preview table for changes) available in the flyout for a field is already available in the table, so this seems easiest for now to avoid multiple logic forks wrapping buttons etc.

E.g. flyout vs table

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: 8b234de

Failed CI Steps

• FTR Configs #103
• FTR Configs #103
• FTR Configs #103

Test Failures

• [job] [logs] FTR Configs #103 / serverless observability UI Dataset Quality Dataset quality summary shows poor, degraded and good count as 0 and all dataset as healthy
• [job] [logs] FTR Configs #103 / serverless observability UI Dataset Quality Dataset quality summary shows poor, degraded and good count as 0 and all dataset as healthy
• [job] [logs] FTR Configs #103 / serverless observability UI Dataset Quality Dataset quality summary shows poor, degraded and good count as 0 and all dataset as healthy

The CI Stats report is too large to be displayed here, check out the CI build annotation for this information.

History

• 💛 Build #264356 was flaky 9eafd43

cc @Kerry350

[kibanamachine]

Starting backport for target branches: 8.x

https://github.com/elastic/kibana/actions/runs/12670671317

[kibanamachine]

💔 All backports failed

Status	Branch	Result
❌	8.x	Backport failed because of merge conflicts You might need to backport the following PRs to 8.x: - [Streams] Dashboard linking (#204309)

Manual backport

To create the backport manually run:

node scripts/backport --pr 205609

Questions ?

Please refer to the Backport tool documentation