Prepare for testmo retries

[maximyurchuk]

Changelog entry

• all testmo interaction with proxy
• ignore session finalization result (see screenshot below)

It was evidence then automation:run:complete at first time returned 500 And after second try returned 422 So we just ignore automation:run:complete

Next steps: add retries for 5XX

Changelog category

• Not for changelog (changelog entry is not required)

Additional information

Sample check with tests: https://github.com/ydb-platform/ydb/pull/8496