Revert "Allow IsolatedContext for ChromeOS Terminal."

This reverts commit c686e5630c25873a432db5b6f92c283b0e37cb84.

This is causing a DCHECK:
FATAL chrome[296968:1]: [agent.cc(100)] Check failed: is_isolated_context == value (0 vs. 1)

Bug: b:316274618
Change-Id: I42744129e6a428aa52f09db960a7a670689e5876
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5052001
Auto-Submit: Emil Mikulic <easy@google.com>
Reviewed-by: Fergus Dall <sidereal@google.com>
Commit-Queue: Fergus Dall <sidereal@google.com>
Cr-Commit-Position: refs/heads/main@{#1237842}
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index d3d67d83..c484f16c 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -2418,11 +2418,6 @@
     return true;
   }
 #endif
-#if BUILDFLAG(IS_CHROMEOS_ASH)
-  if (lock_url == chrome::kChromeUIUntrustedTerminalURL) {
-    return true;
-  }
-#endif
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   if (ChromeContentBrowserClientExtensionsPart::AreExtensionsDisabledForProfile(