Some code - especially WebAssembly - does not make use of the code
target vector. Unconditionally reserving 100 entries adds unnecessary
overhead e.g. to jump table patching (~10%). This CL just removes this
reservation.

R=mstarzinger@chromium.org

Bug: v8:8916
Change-Id: I671820f3eb413fa2d03cef4bbf06adfc7a585266
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559868Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60772}