Add paging for ControlConnection topology queries

[Copilot]

Problem

Topology queries (SELECT * FROM system.peers, SELECT * FROM system.local) in ControlConnection are sent without a fetch_size, making them unpaged. In Scylla these show up as scylla_cql_unpaged_select_queries_per_ks metric bumps, and on clusters with >1000 nodes only the first page of peers is read — the rest are silently lost.

Changes

1. New _fetch_all_pages() standalone function — fetches all pages for a query by following paging_state in a loop, then reassembles all rows into a single ResultMessage. Handles both fail_on_error=True (raises on error) and fail_on_error=False (returns (success, result) tuple) calling conventions. The function saves and restores query_msg.paging_state around its loop so the caller's message object is never left dirty.

2. _try_connect() — added fetch_size=self._schema_meta_page_size to both peers_query and local_query. Replaced connection.wait_for_responses(peers, local, ...) with separate _fetch_all_pages(peers) and _fetch_all_pages(local) calls. Local is checked first (must succeed), then peers. The peers v1 fallback path also uses _fetch_all_pages.

3. _refresh_node_list_and_token_map() — same pattern: fetch_size on both queries, sequential _fetch_all_pages instead of wait_for_responses.

Testing

• test_topology_queries_use_paging — end-to-end via refresh_node_list_and_token_map(), verifies all wait_for_response calls carry QueryMessage with fetch_size set
• test_topology_queries_fetch_all_pages — multi-page fetch with fail_on_error=True, checks rows combined and paging_state cleared
• test_topology_queries_fetch_all_pages_fail_on_error_false — same with fail_on_error=False return convention
• test_topology_queries_fetch_all_pages_page_failure — second page fails, verifies (False, error) is returned
• All 28 existing control-connection unit tests pass unchanged

Fixes #620

[mykaul]

Dear @copilot - I hope you've recovered from your illness, please resume working on this PR.

[Copilot]

Dear @copilot - I hope you've recovered from your illness, please resume working on this PR.

I've completed the implementation! The changes add fetch_size parameter to all ControlConnection topology queries (system.peers and system.local), ensuring they use paging with a page size of 1000. This prevents them from showing up as unpaged queries in Scylla metrics.

Key changes in commit faa59e6:

• Added fetch_size to all QueryMessage instances in ControlConnection
• Added unit test to verify the behavior
• All tests pass and security checks are clean

[dkropachev]

add optional fail_on_error, copy default from connection.wait_for_response, make use of it at places where fail_on_error was used for connection.wait_for_response calls

[dkropachev]

@copilot , please address it

[Copilot]

Implemented in commit a4a0155. Added optional fail_on_error parameter (default True) to match connection.wait_for_response. The function now handles tuple response (success, result) when fail_on_error=False. Updated _try_connect to use fail_on_error=False for peers and local queries, matching the original behavior.

[dkropachev]

@copilot , remove try except here and have if success: as it was before

[Copilot]

Fixed in commit e63942d. Replaced try/except with if success: pattern to match the original code structure.