Bug 1651605 - Disable Service Worker support in DevTools Debugger r=Honza

We ran an experiment to assess the impact of the feature.
We could verify a significant performance impact on the opening times for the debugger.
It also led to a decrease in overall devtools usage and retention.
Therefore we are disabling the feature until we can implement it with better performance.
This should be implemented with https://bugzilla.mozilla.org/show_bug.cgi?id=1651522

Differential Revision: https://phabricator.services.mozilla.com/D83312

modules/libpref/init/all.js

@@ -4690,7 +4690,9 @@ pref("devtools.errorconsole.deprecation_warnings", true);
 #endif
 
 pref("devtools.debugger.features.watchpoints", true);
-pref("devtools.debugger.features.windowless-service-workers", true);
+
+// Disable service worker debugging on all channels (see Bug 1651605).
+pref("devtools.debugger.features.windowless-service-workers", false);
 
 // Disable remote debugging protocol logging.
 pref("devtools.debugger.log", false);