Removal of Jenkinsfiles from the repository

[im-konge]

Hi,
for longer time, we are not using the Jenkinsfile inside this repository, so it was removed in #11196.
I'm curious if we can do the same for PPC and Z architectures?

[Frawless]

cc @kun-lu20 and @Vaibhav-Nazare as you did the latest changes to the READMEs. It seems that available Jenkins instances contains just these jobs and from my POV it is not much maintained (regarding the failures). Based on the current pipeline config it also relies on unmaintained plugin so maybe you can think about better way how to run the tests on ppc and s390x?