Remove references when deleting resources

If you have a biome with a feature in it, and delete said feature, the feature will disappear from the biome's feature list but will still be in the actual file, causing the server to crash when loading the datapack, saying the feature is missing:

.... [21:59:08 ERROR]: Encountered an unexpected exception
com.google.gson.JsonParseException: Error loading registry data: Missing value [7] : ResourceKey[minecraft:worldgen/configured_feature / stovan:lantern_shroom]
at net.minecraft.core.RegistryAccess.lambda$readRegistry$6(RegistryAccess.java:221) ~[app:?]
at java.util.Optional.ifPresent(Optional.java:178) ~[?:?]
at net.minecraft.core.RegistryAccess.a(RegistryAccess.java:221) ~[app:?]
at net.minecraft.core.RegistryAccess.load(RegistryAccess.java:212) ~[app:?]
at net.minecraft.resources.RegistryReadOps.createAndLoad(RegistryReadOps.java:57) ~[patched_1.17.1.jar:git-Paper-295]
at net.minecraft.resources.RegistryReadOps.createAndLoad(RegistryReadOps.java:51) ~[patched_1.17.1.jar:git-Paper-295]
at net.minecraft.server.MinecraftServer.loadWorld(MinecraftServer.java:527) ~[patched_1.17.1.jar:git-Paper-295]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:306) ~[patched_1.17.1.jar:git-Paper-295]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1212) ~[patched_1.17.1.jar:git-Paper-295]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:319) ~[patched_1.17.1.jar:git-Paper-295]
at java.lang.Thread.run(Thread.java:831) ~[?:?]