[core] Don't change log level of global logger

[t1m0thyj]

Calling logging.getLogger().setLevel may have undesired effects on applications using the SDK:

zowe-client-python-sdk/src/core/zowe/core_for_zowe_sdk/credential_manager.py

Line 83 in 58178c0

logging.getLogger().setLevel(logging.ERROR)

The warning we are trying to hide comes from the Python keyring package when used on Windows:
https://github.com/jaraco/keyring/blob/af7233958ece36da8d493509a6388484f5534dfc/keyring/backends/Windows.py#L56-L59

We could investigate using the warnings.filterwarnings method instead to hide only the "Retrieved an UTF-8 encoded credential" warning and continue to log other ones.

[github-actions]

Thank you for creating a bug report.
We will investigate the bug and evaluate its impact on the product.
If you haven't already, please ensure you have provided steps to reproduce the bug and as much context as possible.

[t1m0thyj]

Fixed in 70d62ee since we no longer use the keyring package