Update RN versions we use for e2e tests

[linear[bot]]

When bumping core (getsentry/sentry-react-native#5181), we updated some tests and disabled running tests against older RN versions.

For example:

1. The react-native-test step currently runs only against RN 0.81.0.
2. The react-native-build step builds our app using RN 0.71.11 and 0.81.0, with both Hermes and JSC (though JSC is probably no longer widely used).

However, the version selection was mostly arbitrary — we included the newer version (0.81), but otherwise it would be better to test against the RN versions most commonly used by our customers instead of 0.71.11.

As part of this issue, it would be great to also consider:

1. How the metrics step is implemented and what could be improved.
2. Which engines we should support (Hermes & JSC, or just Hermes).
3. Whether we still need to test against the old architecture.

[linear[bot]]

RN-393