Fix LeakCanary startup in debug builds and fix a memory leak

[Stypox]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

• According to the stacktrace provided in Update LeakCanary library #10085 (comment), LeakCanary now takes care to install the AppWatcher by itself, so we don't need to set it up manually, so I just removed the incriminating line. Also see Fix LeakCanary crash #10231 and this changelog.
• I have tested by enabling LeakCanary in the settings and capturing a few leaks. Among those leaks I then found a really suspicious PlayerService-related leak and I decided to fix it, for more info see https://stackoverflow.com/q/63787707 and the leak report below. You can verify that this was fixed by opening the player, closing it and then taking a heap dump from LeakCanary. Note that these steps did not always lead to the leak before, idk why. Remember to close the app after you enable LeakCanary in debug settings!
• I also set all LeakCanary dependencies as debugImplementation only, as it does not make sense to include those in release builds. Previously they were included just because BaseFragment.onDestroy() called AppWatcher.expectWeaklyReachable(this), but I don't think we need to do it manually, since LeakCanary already takes care of detecting fragments being destroyed. After removing this manual call, I still saw some leaks being detected because "[...] MainFragment received onDestroyView", so I guess the automatic detection works. The release builds fine, here is a release APK signed by me:

The leak report I fixed

┬───
│ GC Root: Global variable in native code
│
├─ org.schabi.newpipe.player.PlayerService$LocalBinder instance
│ Leaking: UNKNOWN
│ Retaining 6.8 kB in 103 objects
│ this$0 instance of org.schabi.newpipe.player.PlayerService
│ ↓ PlayerService$LocalBinder.this$0
│ ~~~~~~
╰→ org.schabi.newpipe.player.PlayerService instance
​ Leaking: YES (ObjectWatcher was watching this because org.schabi.newpipe.
​ player.PlayerService received Service#onDestroy() callback and Service
​ not held by ActivityThread)
​ Retaining 6.3 kB in 102 objects
​ key = cd33af62-1bd6-4297-bc44-2f05fab9fa16
​ watchDurationMillis = 19136
​ retainedDurationMillis = 14120
​ mApplication instance of org.schabi.newpipe.DebugApp
​ mBase instance of org.schabi.newpipe.player.AudioServiceLeakFix

METADATA

Build.VERSION.SDK_INT: 33
Build.MANUFACTURER: Google
LeakCanary version: 2.12
App process name: org.schabi.newpipe.debug
Class count: 30345
Instance count: 297963
Primitive array count: 185241
Object array count: 45771
Thread count: 74
Heap total bytes: 40216348
Bitmap count: 55
Bitmap total bytes: 10275621
Large bitmap count: 0
Large bitmap total bytes: 0
Db 1: open /data/user/0/org.schabi.newpipe.debug/databases/newpipe.db
Db 2: open /data/user/0/org.schabi.newpipe.debug/databases/exoplayer_internal.db
Db 3: open /data/user/0/org.schabi.newpipe.debug/no_backup/androidx.work.workdb
Stats: LruCache[maxSize=3000,hits=136480,misses=286718,hitRate=32%]
RandomAccess[bytes=15166205,reads=286718,travel=153801922092,range=44549734,size
=57029441]
Analysis duration: 24471 ms

Fixes the following issue(s)

• See Update LeakCanary library #10085 (comment)
• Replaces Fix LeakCanary crash #10231

APK testing

The APK can be found by going to the "Checks" tab below the title. On the left pane, click on "CI", scroll down to "artifacts" and click "app" to download the zip file which contains the debug APK of this PR. You can find more info and a video demonstration on this wiki page.

Due diligence

• I read the contribution guidelines.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[TacoTheDank]

@TobiGr Oh yes, thanks for creating a label for dependency stuff. That was something I had in mind a couple of times, but never got around to.