ccmlib/scylla_node: use workdir option

[margdoc]

Use the workdir option to set all subdirectories instead of setting them separately. This change allows to set options dependent on the work directory, for example, maintenance-socket.

[kbr-scylla]

Please prove that this doesn't break dtests by providing a Jenkins run incorporating this change that runs at least the next-gating subset of dtests

[margdoc]

v2:

• discard setting maintenance-socket option (it will be done in scylla)

[margdoc]

v3:

• fixed comment and added comment about dtests.

[margdoc]

Please prove that this doesn't break dtests by providing a Jenkins run incorporating this change that runs at least the next-gating subset of dtests

Ok, this PR is a draft until Jenkins run is provided.

[margdoc]

v4:

• added comment about the use of "workdir,W"
• use data_file_directories option

[margdoc]

Successful Jenkins run with these changes: https://jenkins.scylladb.com/job/scylla-master/job/byo/job/byo_build_tests_dtest/2103/

[margdoc]

@fruch ping

[kbr-scylla]

Merge freeze is over, @fruch can you merge?