this is perfectly fine to use, and preferable to getting a cyclic ref to the scheduler. TaskScheduler->cancelTask() does pretty much the exact same thing, and the scheduler internals are designed to deal with this anyway.
This change breaks pretty much all API pertaining to synchronous task scheduling.
Significant changes:
- Server->getScheduler() has been removed
- Plugin->getScheduler() has been added - every plugin now has its own scheduler
- Because schedulers are now per-plugin, it is now unnecessary for PluginTask to exist because stopping plugin tasks on plugin disable is as simple as destroying the plugin's scheduler. Therefore PluginTask has now been removed and it is expected for things to now use the base Task class instead.
For the most part, plugins will simply need to change Plugin->getServer()->getScheduler()->... to Plugin->getScheduler()->...
Another highlight is that plugin tasks now no longer have global IDs - they are unique to each scheduler.
It is confusing for some developers to whether to use this function or `ServerScheduler::cancelTask($taskId)`. It is better to add warning in the documentation.
