Bug 1976656 - Enable Integrity-Policy by default for scripts. r=freddyb

Differential Revision: https://phabricator.services.mozilla.com/D257055

Author: FKLC

dom/security/test/mochitest/integrity-policy/mochitest.toml

@@ -1,6 +1,7 @@
 [DEFAULT]
 prefs = [
   "security.integrity_policy.enabled=true",
+  "security.integrity_policy.stylesheet.enabled=true",
 ]
 
 ["test_console_messages.html"]

modules/libpref/init/StaticPrefList.yaml

@@ -17286,12 +17286,12 @@
 
 - name: security.integrity_policy.enabled
   type: RelaxedAtomicBool
-  value: false
+  value: @IS_NIGHTLY_BUILD@
   mirror: always
 
 - name: security.integrity_policy.stylesheet.enabled
   type: RelaxedAtomicBool
-  value: true
+  value: false
   mirror: always
 
 # Which mechanism the secret decoder ring should use for encryption. Decryption