[tech debt] use default kerberos ticket cache (instead of hardcoded FILE:/var/tmp/crw-build_ccache)

After we branch for 2.15, we can switch from using the current hardcoded FILE:/var/tmp/crw-build_ccache ticket cache file to whatever the OS uses by default. This will impact:

• ansible scripts - .bashrc and crontab
• util2.groovy / util.groovy
• .jenkinsfile / .sh scripts used for builds

Lots of testing to verify everything works afterwards, for the 4 types of builder nodes:

• s390x
• ppc64le
• x64 permanent
• x64 dynamic (PSI)