[Core] Disconnect one-shot signals before calling callbacks

This prevents infinite recursion with one-shot connections emitting
themselves

modules/gdscript/tests/scripts/runtime/features/emit_after_await.gd

@@ -0,0 +1,12 @@
+# https://github.com/godotengine/godot/issues/89439
+extends Node
+
+signal my_signal
+
+func async_func():
+	await my_signal
+	my_signal.emit()
+
+func test():
+	async_func()
+	my_signal.emit()

modules/gdscript/tests/scripts/runtime/features/emit_after_await.out

@@ -0,0 +1 @@
+GDTEST_OK

modules/gdscript/tests/scripts/runtime/features/emit_one_shot_is_non_recursive.gd

@@ -0,0 +1,22 @@
+# https://github.com/godotengine/godot/issues/89439
+
+signal my_signal
+
+func foo():
+	print("Foo")
+	my_signal.emit()
+
+func bar():
+	print("Bar")
+
+func baz():
+	print("Baz")
+
+func test():
+	@warning_ignore("return_value_discarded")
+	my_signal.connect(foo, CONNECT_ONE_SHOT)
+	@warning_ignore("return_value_discarded")
+	my_signal.connect(bar, CONNECT_ONE_SHOT)
+	@warning_ignore("return_value_discarded")
+	my_signal.connect(baz)
+	my_signal.emit()

modules/gdscript/tests/scripts/runtime/features/emit_one_shot_is_non_recursive.out

@@ -0,0 +1,5 @@
+GDTEST_OK
+Foo
+Baz
+Bar
+Baz