Add a setting to fully disable background PR state polling (causes editor to jump/scroll on focus regain) #9077

Summary

ReviewManager polls for PR state changes on a hardcoded schedule with no way to disable it:

// src/view/reviewManager.ts
private static readonly MIN_POLL_INTERVAL_MS = 1000 * 60 * 5;   // 5 min
private static readonly MAX_POLL_INTERVAL_MS = 1000 * 60 * 30;  // 30 min

pollForStateChange() is started unconditionally in the constructor and re-armed on every onDidChangeWindowState focus event (with 15-60s jitter). There is no vscode.workspace.getConfiguration(...) check anywhere in this path - polling cannot be turned off short of patching the extension.

Impact

In a workspace with many git repositories (e.g. a monorepo with dozens of submodules - each gets its own FolderRepositoryManager/ReviewManager), regaining window focus causes every repo's poller to fire in a burst. For the repo with the actively checked-out PR, if hasNewPullRequests() reports activity, updateState() re-resolves the PR and re-applies CommentThreads on any currently open file with review comments. Recreating those comment threads forces VS Code to re-layout the editor, which visibly scrolls/jumps the cursor - repeatedly, every time focus returns and backoff hasn't kicked in yet.

This is a recurrence of the same user-visible symptom reported in #4159 (duplicate of #4031, fixed in 0.54.0 for a different repro involving GitLens) - but the underlying mechanism (periodic background refresh disturbing editor state) has no off switch today.

Request

Add a setting (e.g. githubPullRequests.disableBackgroundPolling or similar) to disable the automatic poll entirely, relying on the existing manual refresh command instead. Note that manual refresh already goes through a separate updateState() call path, not through doPoll(), so this wouldn't need to touch that.

Environment

• VS Code: 1.141.1
• Extension: GitHub Pull Requests and Issues
• Workspace: multi-repo (submodules), Remote