azure-lb: Don't redirect nc listener output to pidfile

The `lb_start()` function spawns an `nc` listener background process
and echoes the resulting pid to `$pidfile`. Due to a bug in the
redirection, all future data received by the `nc` process is also
appended to `$pidfile`.

If binary data is received later and appended to `$pidfile`, the
monitor operation fails when `grep` searches the now-binary file.

```
line 97: kill: Binary: arguments must be process or job IDs ]
line 97: kill: file: arguments must be process or job IDs ]
line 97: kill: /var/run/nc_PF2_02.pid: arguments must be process or job
    IDs ]
line 97: kill: matches: arguments must be process or job IDs ]
```

Then the start operation fails during recovery. `lb_start()` spawns a
new `nc` process, but the old process is still running and using the
configured port.

```
nc_PF2_02_start_0:777:stderr [ Ncat: bind to :::62502: Address
    already in use. QUITTING. ]
```

This patch fixes the issue by removing the `nc &` command from the
section whose output gets redirected to `$pidfile`. Now, only the `nc`
PID is echoed to `$pidfile`.

Resolves: RHBZ#1850778
Resolves: RHBZ#1850779

Author: nrwahl2

heartbeat/azure-lb

@@ -113,7 +113,8 @@ lb_start() {
 	if ! lb_monitor; then
 		ocf_log debug "Starting $process: $cmd"
 		# Execute the command as created above
-		eval "$cmd & echo \$!" > $pidfile
+		$cmd &
+		echo $! > $pidfile
 		if lb_monitor; then
 			ocf_log debug "$process: $cmd started successfully, calling monitor"
 			lb_monitor