Remove suid bit from Docker image files to mitigate Stack Clash

[mieciu]

Summary

This PR removes suid bit from binaries of Kibana Docker image in order to mitigate "Stack Clash" vulnerability (ref: https://blog.qualys.com/securitylabs/2017/06/19/the-stack-clash). As the image is based on CentOS, there are few of those:

$ docker run --user=0 --rm -i -t docker.elastic.co/kibana/kibana:7.5.0 find / -xdev -perm -4000
/usr/bin/passwd
/usr/bin/umount
/usr/bin/chfn
/usr/bin/su
/usr/bin/chsh
/usr/bin/newgrp
/usr/bin/gpasswd
/usr/bin/chage
/usr/bin/mount
/usr/sbin/unix_chkpwd
/usr/sbin/pam_timestamp_check
/usr/libexec/dbus-1/dbus-daemon-launch-helper

Related: #52450

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 3749fee

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@elasticmachine merge upstream