refactor(ios): remove dead SentrySDKWrapper init surface

`SentrySDKWrapper.createOptionsWithDictionary:isSessionReplayEnabled:error:`
(and `setupWithDictionary:`, `startWithOptions:`, `enableAutoSessionTracking`,
`enableWatchdogTerminationTracking`) became dead when v8 moved init to
`RNSentryStart` (#5582 / #4442). The dead methods had a parallel test suite
that kept passing, which is exactly how the bugs in #6012 and #6014 shipped:
new code was added to `SentrySDKWrapper` because the tests there made it look
like the live surface.

Delete the dead methods, migrate the still-relevant test coverage to
`RNSentryStart`-based tests, drop duplicate tests already pinned on
`RNSentryStart`. `SentrySDKWrapper.h` is not in the podspec's
`public_header_files`, so no downstream consumers are affected. The kept
methods (`configureScope:`, `crash`, `close`, `crashedLastRun`, `debug`,
`releaseName`) continue to be used from `RNSentry.mm`.

Closes #6015.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antonis