Add missing breaking change for http client property removal

[jhlodin]

Description

The linked airlift PR removed the http-client.max-connections property. This was reflected in the Trino documentation with #20101 but should have been given a breaking change since the property was applied by some users.

Additional context and related issues

#20966 #20797

Release notes

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## Section
* Fix some things. ({issue}`issuenumber`)