Make sure debug assertions work in tests

[lann]

We currently run a lot of tests with --release for performance reasons (wasmtime cranelift compile times):

spin/Makefile

Lines 57 to 76 in 291316d

	# Run the runtime tests without the tests that use some sort of assumed external dependency (e.g., Docker, a language toolchain, etc.)
	.PHONY: test-runtime
	test-runtime:
	cargo test --release runtime_tests --no-default-features --no-fail-fast -- --nocapture
	# Run all of the runtime tests including those that use some sort of assumed external dependency (e.g., Docker, a language toolchain, etc.)
	.PHONY: test-runtime-full
	test-runtime-full:
	cargo test --release runtime_tests --no-default-features --features extern-dependencies-tests --no-fail-fast -- --nocapture
	# Run the integration tests without the tests that use some sort of assumed external dependency (e.g., Docker, a language toolchain, etc.)
	.PHONY: test-integration
	test-integration: test-runtime
	cargo test --release integration_tests --no-default-features --no-fail-fast -- --nocapture
	# Run all of the integration tests including those that use some sort of assumed external dependency (e.g., Docker, a language toolchain, etc.)
	.PHONY: test-integration-full
	test-integration-full: test-runtime-full
	cargo test --release integration_tests --no-default-features --features extern-dependencies-tests --no-fail-fast -- --nocapture

One major downside of this is that it disables debug assertions, which we definitely would rather have enabled for testing.

@alexcrichton has suggested that we can probably mitigate the performance issues by selectively enabling optimizations just for cranelift, e.g.:

[profile.test.package.cranelift-codegen]
opt-level = 3

I would probably do the same for [profile.dev] as well, for the same reasons.

Another option would be to continue testing with --release and selectively enable debug-assertions when testing, but there are other reasons to avoid --release such as - ironically - making compilation of the tests themselves faster.