This reverts commit c5c447d4.

Reason for revert: Race condition
https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux/26284

Original change's description:
> [wasm] Enable --wasm-shared-engine by default.
> 
> R=​titzer@chromium.org
> BUG=v8:7424
> 
> Change-Id: I3bb3be92b6c1bf855904cf0bf334ad98dce74dd4
> Reviewed-on: https://chromium-review.googlesource.com/1156310
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54855}

TBR=mstarzinger@chromium.org,titzer@chromium.org

Change-Id: I46b00693b087af0076c634480c15ab109dcbbcce
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7424
Reviewed-on: https://chromium-review.googlesource.com/1160241Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54856}