connections.cgi: Fix Expires time Heading in Connections cgi page

- The Expires time heading for the Connections WUI page has seconds listed. However the
   code is converting the seconds to hours:minutes:seconds.
- This patch is changing the heading to H:M:S in English and the equivalent in the other
   languages. I have basewd this on the initial letter for Hours, Minutes & Seconds in
   each of the languages.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>

langs/pl/cgi-bin/pl.pl

@@ -912,6 +912,7 @@
 'hour-graph' => 'Godzina',
 'hours' => 'Godziny',
 'hours2' => 'Godziny',
+'hours:minutes:seconds' => 'G:M:S',
 'icmp selected but no type' => 'Wybrano protokół ICMP, ale nie określono typu ICMP.',
 'icmp type' => 'Typ ICMP',
 'id' => 'ID',
@@ -1533,7 +1534,6 @@
 'secondary dns' => 'Zapasowy DNS:',
 'secondary ntp server' => 'Zapasowy serwer NTP',
 'secondary wins server address' => 'Adres zapasowego serwera WINS',
-'seconds' => 'Sek',
 'section' => 'Sekcja',
 'secure shell server' => 'Secure Shell Server',
 'security' => 'Bezpieczeństwo',