fix: add teardown logic to clean up Docker networks in tastora tests

[hawkadrian]

Fixes #4643

Adds proper teardown logic to tastora test suites to clean up Docker networks after test completion.

Changes:

• Add Cleanup() method to Framework that stops all nodes and removes Docker network
• Add TearDownSuite() methods to BlobTestSuite and E2ESanityTestSuite
• Prevents accumulation of unused Docker networks (tastora-*)