Refactor test to minimally depende on JS SDK internals

[krystofwoldrich]

Description

Currently, we use a lot of mocked classes and we depend on the internal structure of the JS SDK, this leads to several tests breaking when we upgrade to a newer JS SDK.

• This should not happen unintentionally, if the test intention was to test RN SDK implementation it should not depend on JS internals.

• In cases where the JS SDK internal is crucial to RN SDK and its change would break RN we should add a separate test.

Example of tests to change:

• Should not mock the Hub and Scope https://github.com/getsentry/sentry-react-native/blob/27ab160fa88e6e13afd218176946e60291cff1a4/test/tracing/gesturetracing.test.ts#L31-L70
• The same https://github.com/getsentry/sentry-react-native/blob/27ab160fa88e6e13afd218176946e60291cff1a4/test/tracing/reactnativetracing.test.ts#L56-L102