Fix register search attributes when starting server

[rodrigozhou]

What was changed

Fix register search attributes when starting server

Why?

Currently, search attributes are registered after the server is ready, which can cause race condition with other processes waiting for the server to become ready too. This PR fixes this by registering the search attributes together with the namespaces.

Address temporalio/temporal#6195

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?

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[cretz]

Thanks! LGTM, but not approving because we cannot merge an untagged server version.

[cretz]

We won't be able to merge this until it is in a tagged version. If it only lands in a non-stable tagged version (i.e. 1.26 series and not one of the 1.25 patches), we will need to change the branch this is targeting to next (once that branch is created).

[josh-berry]

The branch exists (it's called next-server).

[cretz]

👍 So once this is in a tagged non-GA version, this can be updated and the target if this PR can be changed to target that branch (or we can close and recreate the PR if preferred).

[rodrigozhou]

Updated the base branch to next-server.

[cretz]

LGTM, but not marking this approved until on tagged server. There seem to be other tests the latest server is breaking.

[cretz]

This LGTM. We have now resolved to not make future server tags depending on SDK/API commit hashes. So when next-server makes it into main we should of course have stable tags for everything.