Make tests mock @bazel_tools by using the directory name "embedded_tools"

This matches what we use in prod, and obviates the need for extra mocking setup for bzlmod as long as you point installDir at the correct mocked directory.

Also cleaned up some duplicated setup code in BuildViewTestCase and ConfigurationTestCase.

PiperOrigin-RevId: 387784879
diff --git a/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java b/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
index 1d8fb65..1b016c2 100644
--- a/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
+++ b/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
@@ -100,7 +100,7 @@
   /** The workspace repository label under which built-in tools reside. */
   public static final String TOOLS_REPOSITORY = "@bazel_tools";
   /** The file path in which to create files so that they end up under {@link #TOOLS_REPOSITORY}. */
-  public static final String TOOLS_REPOSITORY_SCRATCH = "bazel_tools_workspace/";
+  public static final String TOOLS_REPOSITORY_SCRATCH = "embedded_tools/";
 
   /** The output file path prefix for tool file dependencies. */
   public static final String TOOLS_REPOSITORY_PATH_PREFIX = "external/bazel_tools/";
@@ -139,7 +139,7 @@
   public static final String PLATFORM_PACKAGE_ROOT = "@bazel_tools//platforms";
   public static final String CONSTRAINTS_PACKAGE_ROOT = "@platforms//";
 
-  public static final String PLATFORMS_PATH = "bazel_tools_workspace/platforms";
+  public static final String PLATFORMS_PATH = "embedded_tools/platforms";
   public static final String CONSTRAINTS_PATH = "platforms_workspace";
   public static final String LOCAL_CONFIG_PLATFORM_PATH = "local_config_platform_workspace";