Fix annota-input-while-running.exp remote check

Fix annota-input-while-running.exp remote check

The comment says that we can't use runto_main here becore it doesn't
know how to handle annotation.  Instead, the test puts a breakpoint at
main and calls run by hand.  Therefore, it can't work with stub targets,
since they can't "run".  The check should be then changed to check the
use_gdb_stub variable instead of [is_remote target].

But as an alternative, we can just use runto_main and enable annotations
after, since the "run to main" part is not really part of what we want
to test.

I also removed the "set test..." line that is unused.

gdb/testsuite/ChangeLog:

	* gdb.base/annota-input-while-running.exp: Don't check for
	[is_remote target].  Enable annotations after running to main.
	Remove unused "set test..." line.