This reverts commit 652e32f9.

Reason for revert: speculative revert due to flaky test failures:
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20nosnap%20-%20debug/23920

Original change's description:
> [heap] Make trampoline CodeDataContainers immutable and deduplicate them
> 
> Moves all trampoline CodeDataContainers to read-only space, making them
> immutable. Containers with no 'kind specific flags' set or 'promise
> rejection' flag are deduplicated by replacing them with the new canonical
> CodeDataContainers roots.
> 
> This saves around 36KB from the snapshot.
> 
>     RO_SPACE  NEW_SPACE  OLD_SPACE  CODE_SPACE  MAP_SPACE  LO_SPACE
> old    32048          0     225944      149280      20240         0
> new    32120          0     189344      149280      20240         0
> 
> 
> Bug: v8:7464
> Change-Id: Iedd538a86311ef501cd88c90ec75e1308195762f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1601257
> Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61378}

TBR=ulan@chromium.org,delphick@chromium.org,goszczycki@google.com

Change-Id: Ifaf9987bc3770f9e80701e8d011ab19da5c747ca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7464
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1602877Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61388}