Adding ignore paths to cache test (#49874)

Adding exclusion paths to the Mac builder_cache target to avoid archiving symlinks in the SDKs or other unwanted packages. Symlinks cause issues with the CAS archiving functionality. We have opened a bug for the LUCI team regarding this as well.

Companion CL in recipes is here: https://flutter-review.googlesource.com/c/recipes/+/54110

*List which issues are fixed by this PR. You must list at least one issue.*
Fixes flutter/flutter#141688

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: ricardoamador

.ci.yaml

@@ -128,6 +128,10 @@ targets:
           "builder",
           "git"
         ]
+      ignore_cache_paths: >-
+        [
+          "builder/src/flutter/prebuilts/SDKs"
+        ]
       gclient_variables: >-
         {
           "download_android_deps": "true"