refactor: @angular/compiler/testing is an empty module. (#26940)

It was emptied in [angular#34884](https://github.com/angular/angular/pull/43884/files#diff-a276decfccb83a8fb5eae9b051127ce2e3773c9407992869061a648e7bf1d1e5)

(cherry picked from commit a199ab4)

Author: JeanMeche

packages.bzl

@@ -83,7 +83,7 @@ MDC_PACKAGES = [
 ANGULAR_PACKAGES_CONFIG = [
     ("@angular/animations", struct(entry_points = ["browser"])),
     ("@angular/common", struct(entry_points = ["http/testing", "http", "testing"])),
-    ("@angular/compiler", struct(entry_points = ["testing"])),
+    ("@angular/compiler", struct(entry_points = [])),
     ("@angular/core", struct(entry_points = ["testing"])),
     ("@angular/forms", struct(entry_points = [])),
     ("@angular/platform-browser", struct(entry_points = ["testing", "animations"])),