Cranelift: disable egraphs in fuzzing for now.

As per [this comment], with a few recent discussions it's become clear
that we want to refactor egraphs in a way that will subsume, or make
irrelevant, some of the recent fuzzbugs that have arisen (and likely
lead to others, which we'll want to fix!). Rather than chase these down
then refactor later, it probably makes sense not to spend the human time
or fuzzing time doing so. This PR turns off egraphs support in fuzzing
configurations for now, to be re-enabled later.

[this comment]: bytecodealliance#5126 (comment)

crates/fuzzing/src/generators/config.rs

@@ -163,7 +163,6 @@ impl Config {
             .native_unwind_info(self.wasmtime.native_unwind_info)
             .cranelift_nan_canonicalization(self.wasmtime.canonicalize_nans)
             .cranelift_opt_level(self.wasmtime.opt_level.to_wasmtime())
-            .cranelift_use_egraphs(self.wasmtime.use_egraphs)
             .consume_fuel(self.wasmtime.consume_fuel)
             .epoch_interruption(self.wasmtime.epoch_interruption)
             .memory_init_cow(self.wasmtime.memory_init_cow)
@@ -371,7 +370,6 @@ impl<'a> Arbitrary<'a> for Config {
 #[derive(Arbitrary, Clone, Debug, Eq, Hash, PartialEq)]
 pub struct WasmtimeConfig {
     opt_level: OptLevel,
-    use_egraphs: bool,
     debug_info: bool,
     canonicalize_nans: bool,
     interruptable: bool,