They are currently de-facto noexcept as std::terminate is called if commit or rollback throw. But we should make this explicit for users implementing this interface by changing the interface to use the noexcept keyword.

After SERVER-68256 we have four implementations of iterating and invoking callbacks:

• _executeCommitHandlers()
• _executeRollbackHandlers()
• _executeOpenSnapshotHandlers()
• _executeCloseSnapshotHandlers()

We should look into providing an abstraction for this.