[php-src] PR #23306: Fix parameter name in the convert_uudecode() warning

Pull Request: https://github.com/php/php-src/pull/23306 Author: lacatoire convert_uudecode() declares its parameter as $string, but its warning names $data: ``` convert_uudecode(): Argument #1 ($data) is not a valid uuencoded string ``` Following the message and calling convert_uudecode(data: 'x') raises Error: Unknown named parameter $data, while string: works. Reproduced on 8.4.22 and 8.5.9. The message is a literal rather than a generated one, which is why it did not follow the parameter. This is the only place in the tree where a hardcoded $data does not match the declared parameter; the other hits (bzcompress, bzdecompress, gmp_import, http_build_query) all belong to functions whose parameter really is named $data. Three tests pinned the old wording and are updated in the same commit. Targeting master rather than a stable branch, since the warning text is observable output.