[improve][broker] Allow dynamically updating topic load timeout - #26781

Motivation

In extreme operating conditions, a topic-loading stage may repeatedly time out. Allow operators to dynamically increase the timeout without restarting brokers, so affected topics can eventually load successfully.

Modifications

Allow dynamically updating topic load timeout

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment