Misc whitespace handling fixes

Also fixes handling of mtu value in Debian networking.

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

overlays/debian.interfaces/internal/debian_interfaces_test.go

@@ -57,7 +57,7 @@ iface wwnet0 inet static
   address 192.168.3.21
   netmask 255.255.255.0
   gateway 192.168.3.1
-  mtu 
+  mtu 1500
 backupFile: true
 writeFile: true
 Filename: secondary
@@ -68,6 +68,6 @@ iface wwnet1 inet static
   address 192.168.3.22
   netmask 255.255.255.0
   gateway 192.168.3.1
-  mtu 
+  mtu 9000
   up ifmetric wwnet1 30
 `

overlays/debian.interfaces/internal/nodes.conf

@@ -7,9 +7,11 @@ nodes:
         ipaddr: 192.168.3.21
         netmask: 255.255.255.0
         gateway: 192.168.3.1
+        mtu: 1500
       secondary:
         device: wwnet1
         hwaddr: 9a:77:29:73:14:f1
         ipaddr: 192.168.3.22
         netmask: 255.255.255.0
         gateway: 192.168.3.1
+        mtu: 9000