Split URL blacklist policy browsertests

The browsertests of URL blacklist policy are moved from
policy_browsertests to a separate file.

Bug: 1084512
Change-Id: I20258570e63d0ddc6b07435f2a75b25195e3af70
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2207207
Commit-Queue: Swapnil Gupta <swapnilgupta@google.com>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#770791}

chrome/test/BUILD.gn

@@ -1055,6 +1055,7 @@ if (!is_android) {
       "../browser/policy/restore_on_startup_policy_browsertest.cc",
       "../browser/policy/safe_browsing_policy_browsertest.cc",
       "../browser/policy/site_isolation_policy_browsertest.cc",
+      "../browser/policy/url_blacklist_policy_browsertest.cc",
       "../browser/portal/portal_browsertest.cc",
       "../browser/predictors/loading_predictor_browsertest.cc",
       "../browser/prefetch/prefetch_browsertest.cc",