Bug 1858143: Replace 'user' with more appropriate term

Mitsuhiro Yoshida caught a 'user' that I had forgotten.

behatnotneeded

Change-Id: I6500a5333f93265085bf4b271429f5e985f32d78

htdocs/lang/en.utf8/auth.php

@@ -17,8 +17,8 @@ $string['wwwroot'] = 'WWW root';
 $string['protocol'] = 'Protocol';
 $string['port'] = 'Port';
 $string['changepasswordurl'] = 'Password-change URL';
-$string['cannotremove']  = "We cannot remove this authentication plugin, as it is the only \nplugin that exists for this institution.";
-$string['cannotremoveinuse']  = "We cannot remove this authentication plugin, as it is being used by some users.\nYou must update their records before you can remove this plugin.";
+$string['cannotremove']  = "We cannot remove this authentication plugin.\nIt is the only plugin that exists for this institution.";
+$string['cannotremoveinuse']  = "We cannot remove this authentication plugin. It is being used by some people.\nYou must update their records before you can remove this plugin.";
 $string['saveinstitutiondetailsfirst'] = 'Please save the institution details before configuring authentication plugins.';
 
 $string['editauthority'] = 'Edit an authority';