scripts, lib: Don't limit traceback lengths to arbitrary values
There appears to have been a lot of copy and pasting of the code
which prints tracebacks upon failure and limits the stack trace to
5 entries. This obscures the real error and is very confusing to the user
it look me an age to work out why some tracebacks weren't useful.
This patch removes the limit, making tracebacks much more useful for
debugging.
[YOCTO #9230]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
