[CSIT] Fix SDC CSIT Run Errors/Warnings & Path Correction

Use of old for loop syntax causing failure in SDC CSIT
"Support for the old for loop syntax has been removed.
Replace ': FOR' with 'FOR', end the loop with 'END',
and remove escaping backslashes."

Testplan.txt path pointing to sanity instead of uiSanity
causing wrong testplan to be executed.

Fix for sdc-helm-validator warning
"Verify That Sdc Helm Validator Responds With Error
For Chart Valid... [ WARN ] Keyword 'RequestsLibrary.Post
Request' is deprecated. Please use `POST On Session` instead."

Issue-ID: SDC-3573
Signed-off-by: matthew-mcneilly <matthew.mcneilly@est.tech>
Change-Id: Idff668b05330eaf685ab519ee2a0d7cd4fed7ceb