Revert "[WV] Removing NOTREACHED to prevent AwComponentInstallerPolicy crash."

This reverts commit 83cba30a40a2d8287a8f077defbfee7f02c0d94e.

Reason for revert: It looks like the linker is optimizing some methods that contain NOTREACHED, making them appear as `AwComponentInstallerPolicy::OnCustomUninstall` even though this should not be possible. The real fix should be to address this incorrect attribution by the linker.

Original change's description:
> [WV] Removing NOTREACHED to prevent AwComponentInstallerPolicy crash.
>
> Recent spikes in crashes have shown that the OnCustomUninstall code
> path for AwComponentInstallerPolicy is unexpectedly reached. The
> NOTREACHED call moved from silent errors to actually crashing on
> non-debug builds. This removes the call to NOTREACHED until
> the unexpected calls to the uninstall method can be stopped.
>
> Test: N/A
> Bug: 390586616
> Change-Id: Idb0b4592546d9e451f951d28bfcb85fd748c0518
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6191091
> Reviewed-by: Nate Fischer <ntfschr@chromium.org>
> Commit-Queue: Adam Walls <avvall@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1410002}

Bug: 390586616
Change-Id: I4b2ae3ac0289e4836f420ed4909928571a9815db
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6195114
Auto-Submit: Adam Walls <avvall@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1410546}