Removes Chromecast-custom-recipe trybots from 10% experimental.

R=phajdan.jr@chromium.org
BUG=468335

Review URL: https://codereview.chromium.org/1026413003

Cr-Commit-Position: refs/heads/master@{#322166}

testing/commit_queue/config.json

@@ -39,12 +39,6 @@
                             "android_amp_rel_tests_recipe": [
                                 "defaulttests"
                             ],
-                            "cast_shell": [
-                                "defaulttests"
-                            ],
-                            "cast_shell_apk": [
-                                "defaulttests"
-                            ],
                             "linux_arm_compile": [
                                 "defaulttests"
                             ],