man: drop whitespace from final <programlisting> lines

In the troff output, this doesn't seem to make any difference. But in the
html output, the whitespace is sometimes preserved, creating an additional
gap before the following content. Drop it everywhere to avoid this.

man/systemd-coredump.xml

@@ -172,7 +172,7 @@ COREDUMP_CMDLINE=/usr/lib64/firefox/firefox -contentproc -childID 5 -isForBrowse
 COREDUMP_CGROUP=/user.slice/user-1000.slice/user@1000.service/app.slice/app-….scope
 COREDUMP_FILENAME=/var/lib/systemd/coredump/core.Web….552351.….zst
 …
-    </programlisting>
+</programlisting>
 
     <para>The following fields are saved (if known) with the journal entry</para>
 
@@ -305,7 +305,7 @@ flags:   ...
 pos:     ...
 flags:   ...
 ...
-        </programlisting>
+</programlisting>
 
         <para>The first line contains the file descriptor number <replaceable>fd</replaceable> and the path,
         while subsequent lines show the contents of