The vendor/.htaccess file added in T180237: Have composer create a .htaccess file in vendor director/rMWVDf15c291164a2: Add .htaccess to disallow web access is present in the REL1_30 branch of mediawiki/vendor, but it is not included in the released 1.30.0 tarball.
I noticed that it was missing when reviewing the 1.27.4 -> 1.30.0 diff while updating the Debian package.