RouterOS - make deploy more resilient

In the case where importing the cert and key removes the files from disk
the existing deploy will fail when it tries to remove those files.  This
still attempts to remove the files but catches the error and moves on instead
of bombing like before.

Similarly, if the deploy had failed before, subsequent deploys would fail
because the script already existed, so it would not be able to create
the script.  This first attempts to remove the script if it exists, and then
creates the script.

deploy/routeros.sh

@@ -137,7 +137,8 @@ routeros_deploy() {
     return $_err_code
   fi
 
-  DEPLOY_SCRIPT_CMD="/system script add name=\"LECertDeploy-$_cdomain\" owner=$ROUTER_OS_USERNAME \
+  DEPLOY_SCRIPT_CMD=":do {/system script remove \"LECertDeploy-$_cdomain\" } on-error={ }; \
+/system script add name=\"LECertDeploy-$_cdomain\" owner=$ROUTER_OS_USERNAME \
 comment=\"generated by routeros deploy script in acme.sh\" \
 source=\"/certificate remove [ find name=$_cdomain.cer_0 ];\
 \n/certificate remove [ find name=$_cdomain.cer_1 ];\
@@ -146,8 +147,8 @@ source=\"/certificate remove [ find name=$_cdomain.cer_0 ];\
 \n/certificate import file-name=$_cdomain.cer passphrase=\\\"\\\";\
 \n/certificate import file-name=$_cdomain.key passphrase=\\\"\\\";\
 \ndelay 1;\
-\n/file remove $_cdomain.cer;\
-\n/file remove $_cdomain.key;\
+\n:do {/file remove $_cdomain.cer; } on-error={ }\
+\n:do {/file remove $_cdomain.key; } on-error={ }\
 \ndelay 2;\
 \n/ip service set www-ssl certificate=$_cdomain.cer_0;\
 \n$ROUTER_OS_ADDITIONAL_SERVICES;\