Change default for tpf option

Change the default of tpf to the same value as the default of xterm's
disallowedPasteControls, because it may be a security risk.

runtime/doc/options.txt

@@ -6290,7 +6290,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Requires an ISO-8613-3 compatible terminal.
 
 						*'termpastefilter'* *'tpf'*
-'termpastefilter' 'tpf'	string	(default: "")
+'termpastefilter' 'tpf'	string	(default: "BS,HT,ESC,DEL")
 			global
 	A comma separated list of options for specifying control characters
 	to be removed from the text pasted into the terminal window. The

src/nvim/options.lua

@@ -2826,7 +2826,7 @@ return {
       deny_duplicates=true,
       vim=true,
       varname='p_tpf',
-      defaults={if_true={vi="", vim=""}}
+      defaults={if_true={vi="", vim="BS,HT,ESC,DEL"}}
     },
     {
       full_name='terse',