VTY: interactive: never look for matching commands on parent node

For interactive telnet VTY, remove the implicit move up to the parent node when
a command did not succeed on the current node level.

When reading config files, this behavior was useful to allow skipping explicit
'exit' commands. (A different patch deals with that.)

In the telnet VTY, this behavior was never necessary. Explicit 'exit' commands
can move to the parent node, and typically uninformed users expect to require
that.

On a telnet VTY, counting indents like for reading config files is not an
option: a user will always type from the first column or may paste some leading
spaces without intended meaning.

After this patch, it is thus no longer possible to paste a complete config
across several node levels directly to a telnet session, unless it contains
'exit' commands.

Change-Id: Id73cba2dd34676bad8a130e9c45e67a272f19588
diff --git a/tests/vty/vty_test.ok b/tests/vty/vty_test.ok
index a9e283d..2b6d5a6 100644
--- a/tests/vty/vty_test.ok
+++ b/tests/vty/vty_test.ok
@@ -36,9 +36,7 @@
 Going to execute 'log stderr'
 Returned: 0, Current node: 7 '%s(config-log)# '
 Going to execute 'line vty'
-Returned: 0, Current node: 9 '%s(config-line)# '
-Going to execute 'log stderr'
-Returned: 0, Current node: 7 '%s(config-log)# '
+Returned: 2, Current node: 7 '%s(config-log)# '
 Going to execute 'end'
 Returned: 0, Current node: 3 '%s# '
 Going to execute 'exit'