Isolate MCP OAuth settings persistence in agent-server tests

[neubig]

The MCP OAuth settings-store tests should keep persistence inside their pytest temporary directory by setting OH_PERSISTENCE_DIR.

Actual Behavior

In tests/agent_server/test_mcp_oauth_store.py, the affected tests create configurations using tmp_path but call get_settings_store() without setting OH_PERSISTENCE_DIR. The settings store therefore falls back to the user default ~/.openhands persistence directory, allowing encrypted MCP OAuth state to be written outside the pytest sandbox.

Reproduce with:

uv run pytest tests/agent_server/test_mcp_oauth_store.py -q

Before this change, the tests did not redirect OH_PERSISTENCE_DIR to tmp_path.

Acceptance Criteria

• Each affected MCP OAuth settings-store test sets OH_PERSISTENCE_DIR to its pytest tmp_path.
• The focused test suite passes with uv run pytest tests/agent_server/test_mcp_oauth_store.py -q.
• Test execution does not write settings or encrypted OAuth state to the user default persistence directory.

This issue was created and updated by an AI agent (OpenHands) on behalf of the user.

[github-actions]

✅ ready-for-dev label applied

This issue meets the readiness criteria and is ready for contribution.
A contributor can now open a PR that links this issue (Fixes #<number>).

This is an automated check — no AI was used to generate this comment.