Revert "Run PDF Searchify only when needed."

This reverts commit 3b8c5826eb9d0f5306648c2b0be8212f6f9cbdd3.

Reason for revert: speculative revert for browser_tests_no_field_trial timeouts on Win10 Tests x64 bot (https://ci.chromium.org/ui/p/chromium/builders/ci/Win10%20Tests%20x64/100935/overview)

Bug: 421574222
Original change's description:
> Run PDF Searchify only when needed.
>
> Do not schedule PDF page for searchify when it has no images and do not
> start PDF Searchify when no page is scheduled for it.
>
> Bug: 421574222
> Change-Id: Idc134c7b007c46e16e0dfc848729da9cd6dc3c84
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6609060
> Commit-Queue: Lei Zhang <thestig@chromium.org>
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1469437}

Bug: 421574222
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ic39959b97575a86cd20041c7b1e740a99e580a59
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6619704
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1469694}