fix: Use 4 digits for hex port

As described in https://www.kernel.org/doc/Documentation/networking/proc_net_tcp.txt
the format of /proc/net/tcp is using 4 digits for the hex port:

46: 010310AC:9C4C 030310AC:1770 01
|      |      |      |      |   |--> connection state
|      |      |      |      |------> remote TCP port number
|      |      |      |-------------> remote IPv4 address
|      |      |--------------------> local TCP port number
|      |---------------------------> local IPv4 address
|----------------------------------> number of entry

So this string pattern is more accurate

wait/host_port.go

@@ -109,7 +109,7 @@ func (hp *HostPortStrategy) WaitUntilReady(ctx context.Context, target StrategyT
 
 func buildInternalCheckCommand(internalPort int) string {
 	command := `(
-					cat /proc/net/tcp{,6} | awk '{print $2}' | grep -i :%x ||
+					cat /proc/net/tcp{,6} | awk "\"{print $2}"\" | grep -i :%04x ||
 					nc -vz -w 1 localhost %d ||
 					/bin/sh -c '</dev/tcp/localhost/%d'
 				)