fix(dhcp): protect inherited handles in OMAPI child

Use xCAT::Utils->xfork so child-side setup or exec failures do not destroy database handles inherited from the caller.

Signed-off-by: Vinícius Ferrão <2031761+viniciusferrao@users.noreply.github.com>

perl-xCAT/xCAT/DHCP/OmapiRunner.pm

@@ -6,6 +6,7 @@ use warnings;
 use File::Temp qw(tempfile);
 use POSIX qw(WNOHANG);
 use Time::HiRes qw(sleep);
+use xCAT::Utils;
 
 sub open_command_file {
     my ($class, $directory) = @_;
@@ -51,7 +52,7 @@ sub run_command_file {
 }
 
 sub _fork {
-    return fork();
+    return xCAT::Utils->xfork();
 }
 
 sub _completion_attempts {