E2E Test Selection:
The changes remove the automatic mockSwapPopularTokens call from the global withFixtures fixture helper, along with the shouldPrefetchSwapTokens option from WithFixturesOptions.

Key findings:

1. shouldPrefetchSwapTokens defaulted to true, meaning ALL tests using withFixtures previously had swap popular tokens automatically mocked.
2. No test was found using shouldPrefetchSwapTokens: false (confirmed by grep), so no test was explicitly opting out.
3. The swap test files that need this mock (unified-ui-wallet-actions.spec.ts, swap-trending-tokens.spec.ts) already call mockSwapPopularTokens directly in their own test-specific mock setup.
4. The change is a cleanup removing a global mock that was applied to all tests but only needed by specific swap tests.

The primary risk is that some swap-related tests may have been implicitly relying on the global mock without setting it up themselves. SmokeSwap tests must be run to validate they still work correctly after this change. SmokeConfirmations is included because swap flows involve transaction confirmations per the tag descriptions.

Performance Test Selection:
These changes are purely to the E2E test framework infrastructure (fixture helper and types). They remove a global mock setup for swap popular tokens. There is no impact on app production code, UI rendering, data loading, or any runtime performance characteristics. No performance tests are needed.