[NEXMANAGE-737] Sota cancel mode with threading event method

[yengliong93]

PULL DESCRIPTION

This PR implements the sota cancel mode using a threading event flag. When the thread is created, it will be added to a thread list.
When the dispatcher receives the sota cancel request, it checks the current running thread and retrieves its sota type. If it is a download-only sota, the dispatcher sets the event flag to issue a cancel request.
Please note that the first inbc command should be terminated before sending inbc cancel command as they will be sharing the same mqtt connection.

Impact Analysis

Info	Please fill out this column
Root Cause	Specifically for bugs, empty in case of no variants
Jira ticket	NEXMANAGE-737

CODE MAINTAINABILITY

• Added required new tests relevant to the changes
• Updated Documentation as relevant to the changes
• PR change contains code related to security
• PR introduces changes that break compatibility with other modules/services (If YES, please provide description)
• Run go fmt or format-python.sh as applicable
• Update Changelog
• Integration tests are passing
• If Cloudadapter changes, check Azure connectivity manually

Code must act as a teacher for future developers

[yengliong93]

Hi @gblewis1, this PR contains the cancel mode with threading.event method. Unfortunately, it's not functioning as expected. More details are in #559 (comment). It seems like the self._cancel_event.set() doesn't reflect in the sub-thread.

[yengliong93]

The threading event method is actually working. Previously, there was only one place to check the event.is_set. The SOTA process was running too quickly, bypassing that check. I have now added another check after self.calculate_and_execute_sota_upgrade(sota_cache_repo). As a result, I can now see the expected SOTA failure after the event is set.

[yengliong93]

@gblewis1 please have a review, thanks.