Revert "Add FieldTrial config for CCTPrewarmTab"

This reverts commit 142d6dd741de539b296f544e33b3787bb9d4a2d5.

Reason for revert:
LUCI Bisection has identified this change as the cause of a test failure. See the analysis: https://ci.chromium.org/ui/p/chromium/bisection/test-analysis/b/5688071267811328

Sample build with failed test: https://ci.chromium.org/b/8747839137674373313
Affected test(s):
[ninja://chrome/android:chrome_public_test_apk/org.chromium.chrome.browser.customtabs.CustomTabActivityTest#testRecreateSpareRendererOnTabClose](https://ci.chromium.org/ui/test/chromium/ninja:%2F%2Fchrome%2Fandroid:chrome_public_test_apk%2Forg.chromium.chrome.browser.customtabs.CustomTabActivityTest%23testRecreateSpareRendererOnTabClose?q=VHash%3A22ee31d7397c1286)

If this is a false positive, please report it at http://b.corp.google.com/createIssue?component=1199205&description=Analysis%3A+https%3A%2F%2Fci.chromium.org%2Fui%2Fp%2Fchromium%2Fbisection%2Ftest-analysis%2Fb%2F5688071267811328&format=PLAIN&priority=P3&title=Wrongly+blamed+https%3A%2F%2Fchromium-review.googlesource.com%2Fc%2Fchromium%2Fsrc%2F%2B%2F5503169&type=BUG

Original change's description:
> Add FieldTrial config for CCTPrewarmTab
>
> Bug: 40286920
> Change-Id: Ic8c5eb621cf3cf3dc84250bc6d423e57ed51243f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5503169
> Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
> Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
> Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1301569}
>

Bug: 40286920
Change-Id: I84346d185e72b0053cca00341451ccc43c1a78db
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5542932
Owners-Override: James Lee <ljjlee@google.com>
Commit-Queue: James Lee <ljjlee@google.com>
Reviewed-by: James Lee <ljjlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1301846}