Update backend service default values

[modular-magician]

Removes google global and regional backend service values for outlier_detection subfields.
Sets the correct default values for google regional backed service for balancing_mode and connection_draining_timeout_sec.

Fixes: hashicorp/terraform-provider-google#13478
Fixes: hashicorp/terraform-provider-google#12299
Fixes: hashicorp/terraform-provider-google#15210
Fixes: hashicorp/terraform-provider-google#17257

• Searched through the issue tracker for an open issue that this either resolves or contributes.
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests). - read only field
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

compute: Updated default values  of `connection_draining_timeout_sec`, `balancing_mode` and `outlier_detection` in `google_compute_region_backend_service` and `google_compute_backend_service`.

Derived from GoogleCloudPlatform/magic-modules#11117