Tab Search: Remove tab_search .gitignore entries

Remove the tab_search directory from .gitignore and custom gitignore
file from tab_search_merge directory as part of source migration effort.

Bug: 1134167
Change-Id: I3082094118a3b2622ca680d0f9c80b4650d1367d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2498826Reviewed-by: Yuheng Huang <yuhengh@chromium.org>
Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Commit-Queue: Roman Arora <romanarora@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820990}

.gitignore

@@ -112,7 +112,6 @@ vs-chromium-project.txt
 /chrome/browser/resources/media_router_internal/
 /chrome/browser/resources/settings_internal/
 /chrome/browser/resources/software_rendering_list
-/chrome/browser/resources/tab_search
 # Asset files downloaded by gclient runhooks.
 /chrome/browser/resources/vr/assets/google_chrome/*.png
 /chrome/browser/resources/vr/assets/google_chrome/*.wav
@@ -165,7 +164,6 @@ vs-chromium-project.txt
 /chrome/test/data/plugin/
 /chrome/test/data/vr/
 /chrome/test/data/webrtc/resources
-/chrome/test/data/webui/tab_search
 /chrome/test/data/xr/ar_playback_datasets/*.mp4
 /chrome/test/data/xr/webvr_info/
 /chrome/test/media_router/internal

chrome/browser/resources/tab_search_merge/.gitignore

-*.bak
-*.mk
-*.ncb
-*.opensdf
-*.orig
-*.pdb
-*.props
-*.pyc
-*.pyproj
-*.rules
-*.sdf
-*.sln
-*.sublime-project
-*.sublime-workspace
-*.suo
-*.targets
-*.user
-*.vc.opendb
-*.vcproj
-*.vcxproj
-*.vcxproj.filters
-*.vpj
-*.vpw
-*.vpwhistu
-*.vtg
-*.xcodeproj
-*.xcworkspace
-*.VC.db
-*_proto.xml
-*_proto_cpp.xml
-*~
-!Android.mk
-.*.sw?
-.DS_Store
-.android
-.ccls-cache
-.cipd
-.classpath
-.code-coverage
-.cproject
-.emulator_sdk
-.gdb_history
-.gdbinit
-.landmines
-.metadata
-.project
-.pydevproject
-.checkstyle
-*.class
-compile_commands.json
-cscope.*
-GPATH
-GRTAGS
-GSYMS
-GTAGS
-Session.vim
-tags
-Thumbs.db
-v8.log
-vs-chromium-project.txt
-/.cache/
-/.clangd/
-/.clangd-index/
-# Settings directories for eclipse
-/.externalToolBuilders/
-/.settings/
-/.vs/
-# Visual Studio Code
-.vscode/
-/_out
-/android_emulator_sdk
-/ash/ash_unittests_run.xml
-/base/base_unittests_run.xml
-/.cache/
-# Ignore IntelliJ files.
-.idea/
-# Ignore cache folder created by clangd
-.cache