[dPWA] Clean up PreinstalledWebAppDuplicationFixer

This CL cleans up the PreinstalledWebAppDuplicationFixer start up
adjustment step.
This looked for preinstalled web apps that had corresponding old
Chrome apps still installed and re-migrated them. This was very
successful when deployed and has tapered off substantially,
see metrics: go/nejyv

This code is a complexity risk to keep around and can cause other
unintended issues at start up, see crbug.com/1393284 for an example.

Bug: 1290716
Change-Id: I3d16034e7a2ea871e1be735aecc9c5903b647207
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4584075
Reviewed-by: Dibyajyoti Pal <dibyapal@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1153622}

chrome/browser/web_applications/BUILD.gn

@@ -888,10 +888,7 @@ source_set("web_applications_browser_tests") {
 group("browser_tests") {
   testonly = true
 
-  deps = [
-    ":web_applications_browser_tests",
-    "adjustments:adjustments_browser_tests",
-  ]
+  deps = [ ":web_applications_browser_tests" ]
 }
 
 # On Lacros, these browser tests require Ash to be running.

chrome/browser/web_applications/adjustments/BUILD.gn

@@ -6,8 +6,6 @@ import("//chrome/common/features.gni")
 
 source_set("adjustments") {
   sources = [
-    "preinstalled_web_app_duplication_fixer.cc",
-    "preinstalled_web_app_duplication_fixer.h",
     "web_app_adjustments.cc",
     "web_app_adjustments.h",
   ]
@@ -37,26 +35,6 @@ source_set("adjustments") {
   }
 }
 
-source_set("adjustments_browser_tests") {
-  testonly = true
-
-  sources = []
-
-  if (!is_chromeos_lacros) {
-    sources += [ "preinstalled_web_app_duplication_fixer_browsertest.cc" ]
-  }
-
-  defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
-
-  deps = [
-    ":adjustments",
-    "//chrome/browser/apps/app_service",
-    "//chrome/browser/web_applications",
-    "//chrome/browser/web_applications:web_applications_test_support",
-    "//chrome/test:test_support",
-  ]
-}
-
 source_set("unit_tests") {
   testonly = true