Fix CacheUpdate implementations for extra FullEvents #5931

Job	Run time
Test (macOS)	54s
Build docs	46s
Examples	1m 12s
MSRV	0s
Check minimal versions	32s
Test (nightly)	55s
Test (stable)	52s
Test (beta)	51s
Test (Windows)	3m 13s
Test (native-tls)	1m 14s
Test (no default features)	50s
Test (no cache)	2m 4s
Test (no gateway)	1m 30s
Test (unstable Discord API features)	1m 1s
Test (zlib compression)	51s
Test (zstd compression)	52s
Test (zlib and zstd compression)	52s
Test (chrono, chrono)	58s
Test (unstable API + typesize, default unstable typesize, true)	56s
Test (builder without model, builder, true)	38s
Test (unstable Discord API (no default features), unstable, true)	53s
	21m 54s

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