[CPDEV-93171] - clean kubernetes tmp dir before upgrade

[Imadzuma]

Description

During upgrade procedure kubeadm creates special backup files, that are used for manual restoration.
But no one uses or cleans those files, for this reason they are not really needed and only take up the place on the disk.

Fixes # (issue)

Solution

• Added the special task, that cleans up that directory before upgrade procedure; As result backups only for the last upgrade will be in that directory after the procedure;
• Added information about it in documentation;

Test Cases

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any

TestCase 1

Test Configuration:

• Hardware:
• OS:
• Inventory:

Steps:

1. run kubemarine install;
2. run kubemarine upgrade to one version;
3. check content of /etc/kubernetes/tmp folder on worker and control-plane nodes;
4. run kubemarine upgrade again to another version;
5. check content of /etc/kubernetes/tmp folder again on worker and control-plane nodes;
   Results:

Before	After
files from step 3 are visible for step 5	step 3 and step 5 have different backup files

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Integration CI passed
• Unit tests. If Yes list of new/changed tests with brief description
• There is no merge conflicts

Unit tests

Indicate new or changed unit tests and what they do, if any.

[koryaga]

@shmo1218 pls update afterwards