[pre-7.12] Tribler crashes are not reported to Sentry anymore

[kozlovsky]

During the release preparation, I discovered that Tribler 7.12 does not send crash reports to Sentry anymore:

• Instead of displaying the FeedbackDialog that allows editing crash reports before sending, Tribler shows a simplified message box with minimal error details.

• In the next simplified dialog box, Tribler suggests reporting the error, but even if the user press "Yes", the error is not reported

To reproduce the problem, you can press the Ctrl+O shortcut that triggers a not-yet-fixed bug in GUI, or you can press theCtrl+Alt+Shift+G shortcut that triggers a test GUI error that is handled just like a typical GUI error.

• In case of a Core-related exception, the normal FeedbackDialog shows correctly, but the error still does not get reported to Sentry after the user presses the "Send" button.

The issue should be fixed before the release, or we do not get reports about Tribler crashes.

[kozlovsky]

As it turns out, the reason for the problem was using two instances of SentryReporter, gui_sentry_reporter and default_core_exception_handler.sentry_reporter as described in #6975.

Initially, I implemented the fix in #6975, but then I realized that cherry-picking #6886 from the main branch to the release branch also fixes the problem.

These two PRs solve the problem in a slightly different way. #6975 uses a single default_sentry_reporter through the entire code-base. #6886 takes care to not use gui_sentry_reporter and default_core_exception_handler.sentry_reporter in the same process and correctly initialize the right reporter.

I think there is a benefit in using a single reporter, but to avoid later release->main merge conflicts, it looks more practical to just cherry-pick #6886 and optionally switch to a single reporter later in the main branch.

[kozlovsky]

Fixed in #6976