CDRIVER-3882 Support AWS temporary credentials (#1109)

* Sync legacy CSE test files with b3beada7

* Add legacy CSE test runner support for AWS temp creds

* Update Evergreen config to support AWS temp creds

* Print status during invocation of Drivers Evergreen Tools scripts

* Define PYTHON as PYTHON_BINARY after activate_venv.sh

* Deactivate the kmstlsenv venv environment when done

* Ensure calls to activate_venv.sh do not race on venv preparation

* Replace legacy backtick notation with dollar-parenthesis notation

* Suppress errors on chmod of build dirs