Remove dead binding code regarding Godot 4.0 #3164

Job	Run time
clippy	1m 47s
license-guard	33s
godot-itest (macos)	1m 15s
doc-lints	56s
godot-itest (windows)	3m 1s
godot-itest (linux-full)	2m 23s
run-examples	1m 25s
unit-test	2m 21s
rustfmt	22s
godot-itest (linux-features-experimental)	2m 7s
godot-itest (linux-4.1)	1m 16s
godot-itest (linux-4.2)	1m 6s
godot-itest (linux-memcheck)	2m 9s
ci-status	1s
	20m 42s

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