change: set defi controller to refresh only one account (#6944)

## Explanation

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- Updates DeFiPositionsController to only update the selected EVM
account
- Adds timeout & retry mechanism
- Fixes issue with DeFi polling starting before onboarding due to
subscription to `KeyringController:unlocked` event

Draft PR for extension:
MetaMask/metamask-extension#37215
Draft PR for mobile:
MetaMask/metamask-mobile#21657

## References

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Related to https://consensyssoftware.atlassian.net/browse/ASSETS-1238

## Checklist

- [X] I've updated the test suite for new or updated code as appropriate
- [X] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [X] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [X] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Updates DeFi positions to only refresh the selected EVM address, gates
updates on relevant events, and adds an 8s timeout with a single retry
to the API fetch.
> 
> - **DeFiPositionsController**
> - Refreshes DeFi positions for only the selected EVM account
(`_executePoll`, `#updateAccountPositions`).
> - Replaces AccountsController dependencies with
`AccountTreeController:getAccountsFromSelectedAccountGroup` to derive
selected EVM address.
>   - Event changes:
>     - Stops polling on `KeyringController:lock` (unchanged).
> - Removes `KeyringController:unlock` and
`AccountsController:accountAdded` listeners.
> - Adds `AccountTreeController:selectedAccountGroupChange` to refresh
selected address.
> - `TransactionController:transactionConfirmed` now updates only if it
matches the selected address.
> - **Fetch behavior**
> - `fetch-positions`: wraps API call with `timeoutWithRetry` (8s
timeout, 1 retry).
>   - Adds `utils/timeout-with-retry` with unit tests.
> - **Tests**
> - Update unit tests to new selected-account-only behavior and new
events.
> - **Changelog**
> - Documents breaking changes to events/behavior and new timeout+retry.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
fe03293. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: bergarces

packages/assets-controllers/CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **BREAKING:** Modify DeFi position fetching behaviour ([#6944](https://github.com/MetaMask/core/pull/6944))
+  - The fetch request to the API times out after 8 seconds and attempts a single retry
+  - Refresh only updates the selected evm address
+  - `KeyringController:unlock` no longer starts polling
+  - `AccountsController:accountAdded` no longer updates DeFi positions
+  - `AccountTreeController:selectedAccountGroupChange` updates DeFi positions for the selected address
+  - `TransactionController:transactionConfirmed` only updates DeFi positions if the transaction is for the selected address
+
 ## [86.0.0]
 
 ### Changed