Introduce EndsWithBye log analysis check

It was initially foreseen to just check the program exit code, but most
executables don't return with 0 (so the CI would always fail). Add a
separate check that will check for the Bye., only going through the last
X lines instead of the entire file.

ci-scripts/tests/log-analysis/with-bye.log

@@ -0,0 +1,3 @@
+Some other logs
+Bye.
+process exited.