Fix known FIXME about BTreeMap Key Cloning

[gabrielbosio]

See https://github.com/lambdaclass/cairo-vm/blob/8d4858689e01d439633375d70b8dc12053680a6a/vm/src/vm/runners/cairo_runner.rs#L1589-L1590 and https://github.com/lambdaclass/cairo-vm/blob/8d4858689e01d439633375d70b8dc12053680a6a/vm/src/vm/runners/cairo_runner.rs#L1610-L1611