wasm: increase memory and attempt to GC in tests

[bakkot]

Attempt to fix #7399.

Just forcing GC or increasing memory size to 2GB alone are each insufficient, but in combination tests pass again at least on my machine. This is not an elegant solution but hopefully at least un-breaks the build. I can try to experiment with newer versions of emscripten or a different test runner if I have time later.

[NikolajBjorner]

Something different is happening. It times out in "can do simple proofs".
I would merge this PR even if it doesn't run to completion because it looks easier to fix than the original code.

[NikolajBjorner]

I get the following now in code spaces:

● Test suite failed to run

RuntimeError: Aborted('PThread' was not exported. add it to EXPORTED_RUNTIME_METHODS (see the Emscripten FAQ))

  887 |   // TODO(https://github.com/google/closure-compiler/pull/3913): Remove if/when upstream closure gets fixed.
  888 |   /** @suppress {checkTypes} */
> 889 |   var e = new WebAssembly.RuntimeError(what);
      |           ^
  890 |
  891 |   readyPromiseReject(e);
  892 |   // Throw the error whether or not MODULARIZE is set because abort is used

  at abort (build/z3-built.js:889:11)
  at Object.get (build/z3-built.js:1200:9)
  at killThreads (src/jest.ts:51:6)
  at Object.<anonymous> (src/high-level/high-level.test.ts:88:22)

Test Suites: 1 failed, 1 passed, 2 total
Tests: 39 passed, 39 total
Snapshots: 0 total
Time: 46.001 s
Ran all test suites.
@NikolajBjorner ➜ .../z3/src/api/js (master) $

[bakkot]

For code spaces, my guess is that the version of emscripten in code spaces is newer than the version in CI. If you do emsdk install 3.1.15 && emsdk activate 3.1.15 does that fix it?

I should update the emscripten version used in CI; it's way behind. But your experience suggests there have been some breaking changes so this might not happen right away.