[Fuchsia] Use isolated-cache for the cdm_data_directory

The ContextParams.cdm_data_directory is provided by the client for the
storage of CDM user data. This CL populates this field for CastRunner
with persistent-isolated-cache. This is temporary to prevent breakage.

Bug: 1051225, b/162078899
Change-Id: Idd291e318ccaf256194ae207018c77c8cfedd574
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2315001
Commit-Queue: RJ Ascani <rjascani@google.com>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799270}
GitOrigin-RevId: 1f7499b3bfa727d3d58265d4d71d7fb51701c171

config/fuchsia/tests-with-exec.cmx

@@ -2,6 +2,7 @@
   "sandbox": {
     "features": [
       "deprecated-ambient-replace-as-executable",
+      "isolated-cache-storage",
       "isolated-persistent-storage",
       "isolated-temp",
       "root-ssl-certificates",

config/fuchsia/tests.cmx

@@ -2,6 +2,7 @@
   "sandbox": {
     "features": [
       "config-data",
+      "isolated-cache-storage",
       "isolated-persistent-storage",
       "isolated-temp",
       "root-ssl-certificates",