reuse requests session when doing api calls

[yabirgb]

Summary

As stated in https://requests.readthedocs.io/en/latest/user/advanced/#session-objects

if you’re making several requests to the same host, the underlying TCP connection will be reused, which can result in a significant performance increase

This commit adjusts the initialization of the Http class and the configuration to create a session object that will be reused across different calls.

In addition self.requests_session.proxies.update(requests.utils.getproxies()) needs to be called only once so now the function is lighter in what it does.

For the removed test I checked the commit that added it and I believe is not needed as the code behaves different, session is not closed now.

I have checked it against the tests in my project and seems to work properly too.

Related to #162

Checklist

• Added changelog entry
• I alphabetized all attributes, parameters, and methods by name in any class file I changed
• Ran unit tests (python3 -m unittest discover tests/unit)
• I have linked the JIRA ticket in the summary section
• I have reviewed the JIRA ticket to ensure all AC's are met
• I understand that unless this is a Draft PR or has a DO NOT MERGE label, this PR is considered to be in a deploy ready state and can be deployed if merged to main