MT#65645 sync-db fix $dbh->begin_work()

change $dbh->begin_work or die "Cannot start tx: "..
to more appropriate
$dbh->begin_work if $dbh->{AutoCommit}
so that the transasction starts only if there is none,
because since some time a shared $dbh object is used.

Change-Id: I2fb6e115c170a5b04a010cb70198182cbbe9712d
(cherry picked from commit cf37b2cba5)
(cherry picked from commit 4550243c3b)

helper/sync-db

@@ -378,7 +378,7 @@ sub do_sync_db_timezones {
 
     my $sql = '';
     try {
-        $dbh->begin_work() or die "Cannot start tx: $DBI::errstr\n";
+        $dbh->begin_work() if $dbh->{AutoCommit};
         my ($cur_tzinfo_version) = $dbh->selectrow_array(<<SQL)
 SELECT version
   FROM ngcp.tzinfo_version
@@ -451,7 +451,7 @@ sub do_sync_timezone_version {
 
     my $sql = '';
     try {
-        $dbh->begin_work() or die "Cannot start tx: $DBI::errstr\n";
+        $dbh->begin_work() if $dbh->{AutoCommit};
         my ($cur_tz_version) = $dbh->selectrow_array(<<SQL)
 SELECT COALESCE(version,'')
   FROM ngcp.timezone