fix(lavalink): drop lavalink.plugins config block, load jars from plugins/ dir

Lavalink 4.2.2 re-downloads/verifies config-declared plugins on startup and
failed writing to the git-managed plugins bind mount (Permission denied,
container uid 322 vs root-owned files after git pull). Jars in the plugins
directory are loaded directly; remove the duplicate config block.

lavalink/application.yml

@@ -32,11 +32,6 @@ plugins:
       playlistLoadLimit: 6
 
 lavalink:
-  plugins:
-    - dependency: "dev.lavalink.youtube:youtube-plugin:1.18.2"
-      repository: "https://maven.lavalink.dev/releases"
-    - dependency: "com.github.topi314.lavasrc:lavasrc-plugin:4.8.3"
-      repository: "https://maven.topi.wtf/releases"
   server:
     password: "Hch4HiVCxkKs9JPiSnrt4Q"
     sources: