Speed up ApiQuerySiteinfoTest:testContinuation
The test fills $wgUrlProtocols with 86000 entries, forging oversized
strings which ends up eventually truncated to 100 bytes. The aim is to
overflow $wgAPIMaxResultSize to trigger an apiwarn-truncatedresult
warning.
The test takes 230 ms on my machine and when generating code coverage
almost a minute.
A faster approach is just to lower the $wgAPIMaxResultSize limit to
trigger the warning.
Test plan:
$ php tests/phpunit/phpunit.php \
tests/phpunit/includes/api/ApiQuerySiteinfoTest.php \
--filter testContinuation
Bug: T234016
Change-Id: I3dc96d394d8b98dda8f151d14544b829c92f9b10