Migrate begin/endEvent try/finally patterns to `Systrace.trace` (#56937)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56937

Migrates existing `Systrace.beginEvent` / `Systrace.endEvent` (and bare `beginEvent`/`endEvent`) try/finally blocks to the new `Systrace.trace` helper, which keeps the same semantics but is more concise.

Other existing `beginEvent`/`endEvent` call sites are left untouched because they have `__DEV__` guards that do not wrap the entire body and would require additional restructuring.

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D106073157

fbshipit-source-id: 3e8328b79ec7c03a6f17c130bfde4489eefdcc33