[Dependency] Bump Go SDK to v0.50.0

[mgyucht]

Changes

Use the latest Go SDK in the Terraform provider. The main changes affect Dashboards and Online Tables, whose Create and Update RPCs now accept an instance of the resource, rather than inlining the fields of the resource. Additionally, Online Tables introduced a waiter configuration, so we can remove hand-written waiter logic used before.

Tests

• [ ] make test run locally
• [ ] relevant change in docs/ folder
• [ ] covered with integration tests in internal/acceptance
• [ ] relevant acceptance tests are passing
• [ ] using Go SDK

[eng-dev-ecosystem-bot]

Test Details: go/deco-tests/11617909939