[browser] memory leaks

[pavelsavara]

Review memory leaks found by ASAN in "hello world" + AOT sample.

Details

SUMMARY: AddressSanitizer: 11164 byte(s) leaked in 535 allocation(s).

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.