Img-proof

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- Add SLES 15 SP4 repos to SLES test suite
- Remove definitions for non existing products
- Remove SLES 11 repo configuration, SLES 11 is EOL

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- Fix GCE auth tests to avoid auth request

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- Force GCE auth to provide a useful error message with invalid credentials

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- Handle breaking changes in cloud-regionsrv-client to fix
SLES registration check.

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- Use -v/--nofsroot option in root grow test to support btrfs
- Account for sle-micro in EC2 Dracut conf test

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- Fix GCE SSH key insertion
- Fix sle-micro integration
- Use strtobool locally instead of from distutils which is deprecated
- Use setup_method in unit tests instead of setup. Setup is no longer
called before every test.
- Fix flake8 formatting error in test suite
- Update grow root test:
+ To handle sle-micro with btrfs root volume
+ To include /var partition in calculation if it exists
+ To allow for small discrepancies due to rounding errors