Fix mem leak in event listeners

[enricohuang]

Purpose

• Fix mem leak due to some event listeners not being removed after call is ended. (events in the device manager layer)
• event listeners in the call context or call features will be removed automatically when the call is ended, so we don't need to unregister them.

Does this introduce a breaking change?

[ ] Yes
[ ] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

• ...

Other Information