azure: fix bootstrap extension command error path for bash

On some distros like for example Flatcar, bootstrap extension command is
executed using bash, instead of using e.g. dash on Ubuntu, which does not
allow 'return' calls from the shell, so when currently provisioning fails,
user gets the following confusing error message:

/bin/sh: line 1: return: can only return' from a function or sourced
script

To fix this, let's use 'exit' instead which should be more universal.

Refs #2271

Signed-off-by: Mateusz Gozdek <[email protected]>

Author: invidian

azure/defaults.go

@@ -103,7 +103,7 @@ const (
 
 var (
 	// LinuxBootstrapExtensionCommand is the command the VM bootstrap extension will execute to verify Linux nodes bootstrap completes successfully.
-	LinuxBootstrapExtensionCommand = fmt.Sprintf("for i in $(seq 1 %d); do test -f %s && break; if [ $i -eq %d ]; then return 1; else sleep %d; fi; done", bootstrapExtensionRetries, bootstrapSentinelFile, bootstrapExtensionRetries, bootstrapExtensionSleep)
+	LinuxBootstrapExtensionCommand = fmt.Sprintf("for i in $(seq 1 %d); do test -f %s && break; if [ $i -eq %d ]; then exit 1; else sleep %d; fi; done", bootstrapExtensionRetries, bootstrapSentinelFile, bootstrapExtensionRetries, bootstrapExtensionSleep)
 	// WindowsBootstrapExtensionCommand is the command the VM bootstrap extension will execute to verify Windows nodes bootstrap completes successfully.
 	WindowsBootstrapExtensionCommand = fmt.Sprintf("powershell.exe -Command \"for ($i = 0; $i -lt %d; $i++) {if (Test-Path '%s') {exit 0} else {Start-Sleep -Seconds %d}} exit -2\"",
 		bootstrapExtensionRetries, bootstrapSentinelFile, bootstrapExtensionSleep)