Set log.Default's output to io.Discard

[ulucinar]

Description of your changes

This PR sets a default io.Discard logger for the controller-runtime if debug logging is not enabled. If debug logging is enabled, then the controller-runtime uses a debug mode zap logger as usual.

It also sets the log.Default's output to io.Discard. According to a test with a ResourceGroup.azure, this prevents the noisy logs from the underlying Terraform provider. We still need to check for direct log messages via the fmt variants, such as fmt.Println.

In a further iteration, we will also consider making the underlying provider's logs available in a structured format.

This PR also fixes the dynamic reference resolution for the MRs in the azure.upbound.io group by passing the -o azure.azure.upbound.io=azure.upbound.io command-line option to the resolver transformer.

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Tested manually with the ResourceGroup.azure resource and the Subnet.network resource via upjet here.

[ulucinar]

/test-examples="examples/azure/resourcegroup.yaml"

[sergenyalcin]

Thanks @ulucinar LGTM! I also validated the provider logs in dumps. We do not print the huge log about the provider configuration anymore. It seems that the size of the dumps are also affected via this change. Before, for the resourcegroup.yaml test, our dump's size is more than 2 MB. Now this is around 600 KB. This is another validation point about the logging improvements.

[turkenf]

/test-examples="examples/network/subnet.yaml"

[ulucinar]

/test-examples="examples/azure/resourcegroup.yaml"

[ulucinar]

/test-examples="examples/network/subnet.yaml"

[ulucinar]

make lint succeeded in a local run...

[github-actions]

Backport failed for release-0.42, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git fetch origin release-0.42
git worktree add -d .worktree/backport-678-to-release-0.42 origin/release-0.42
cd .worktree/backport-678-to-release-0.42
git checkout -b backport-678-to-release-0.42
ancref=$(git merge-base bd59c298108d23e906d9fcbba860507e12cd163e 6790d291dd56eb32c439b2f1b5e7313da6c5b9e3)
git cherry-pick -x $ancref..6790d291dd56eb32c439b2f1b5e7313da6c5b9e3