oeqa/runtime/stap: rewrite test

There's no need to copy files to the target when stap can take the short
probe directly.

Add more has-package decorators for the kernel source and GCC symlinks.
Remove the test dependencies as it's not a hard dependency.

Change the probe to print a message with some minimal logic, and verify
that the message was correctly constructed in the output.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>