Bug 1836255 - Set network.early-hints.preconnect.max_connections to 10 also in non-nightly channels r=necko-reviewers,jesup

This is fine to be always non-zero, because the variable is only read if
network.early-hints.preconnect.preconnect is set to true

Differential Revision: https://phabricator.services.mozilla.com/D179684

modules/libpref/init/StaticPrefList.yaml

@@ -11792,11 +11792,7 @@
 # be limited by "network.http.speculative-parallel-limit".
 - name: network.early-hints.preconnect.max_connections
   type: uint32_t
-#if defined(NIGHTLY_BUILD)
   value: 10
-#else
-  value: 0
-#endif
   mirror: always
 
 # How long we should wait for EarlyHintPreloader to be used.