Revert "[StartSurface] Set incognito description height to match parent"

This reverts commit 9d41ebe6.

Reason for revert: org.chromium.chrome.features.start_surface.StartSurfaceTest#testSearchInIncognitoSingleSurface__Instant_Return is flaky. This cl is causing a merge error to revert the original cl https://crrev.com/c/2252688

Original change's description:
> [StartSurface] Set incognito description height to match parent
> 
> This CL fixes the bug in
> https://chromium-review.googlesource.com/c/chromium/src/+/2243334
> 
> Without setting the height to match_parent, it will be unscrollable
> when its content is short.
> 
> Screen record before
> https://drive.google.com/file/d/1CUOz6ErGL2fxkF2pGAC_fGWEcTGy8hrD/view?usp=sharing
> 
> Screen record after
> https://drive.google.com/file/d/1CeuBtjQbGRovJC8H0Vk-wY6wpWqmlQJ0/view?usp=sharing
> 
> Bug: 1093506
> Change-Id: Iff9df7ef0050885c02fe55676dbfa2046d6e78a0
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2253143
> Commit-Queue: Ganggui Tang <gogerald@chromium.org>
> Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
> Auto-Submit: Ganggui Tang <gogerald@chromium.org>
> Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#780086}

TBR=gogerald@chromium.org,wychen@chromium.org

Change-Id: I7abf532c1da073c32b1c604540c5ef68728587f6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1097002
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2252046Reviewed-by: Tanmoy Mollik <triploblastic@chromium.org>
Commit-Queue: Tanmoy Mollik <triploblastic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780263}

chrome/android/features/tab_ui/java/res/layout/tasks_view_layout.xml

@@ -78,7 +78,7 @@
     <ViewStub
         android:id="@+id/incognito_description_container_layout_stub"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
+        android:layout_height="wrap_content"
         android:layout="@layout/incognito_description_container_layout"
         app:layout_behavior="@string/appbar_scrolling_view_behavior" />