fix(limiter): adjust type for compatibility

[lafirest]

Fixes

this type used to be 0 | float, but here https://github.com/emqx/emqx/blob/d1089fa4603fddd7035a8487515fcabe496acdfa/apps/emqx/src/emqx_limiter/src/emqx_limiter_schema.erl#LL144C68-L144C68, we set a default value of 1000 to the capacity, it should have been stored as a string, but in some configuration files it is a number which will not trigger a typerefl_from_string call and directly pass to the hocon validator, obviously, the 1000 either 0 or float, so the type must be changed to number().

Summary

🤖 Generated by Copilot at 95a67f3

Changed the type of burst_rate in emqx_limiter_schema.erl to support negative values. This allows the rate limiter to borrow tokens from the future.

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Changed lines covered in coverage report
• Change log has been added to changes/{ce,ee}/(feat|perf|fix)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• If there should be document changes, a PR to emqx-docs.git is sent, or a jira ticket is created to follow up
• Schema changes are backward compatible

Checklist for CI (.github/workflows) changes

• If changed package build workflow, pass this action (manual trigger)
• Change log has been added to changes/ dir for user-facing artifacts update