Do not opt-in to NNBD when building application snapshots for kernel service and other tools like dartjs, dart analyzer etc. We should enable this only when all the tools are ready to opt-in.

Change-Id: If7f507d101d006a9e103118c9f989dc9f1b145d0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/133481
Reviewed-by: Liam Appelbe <liama@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>

utils/application_snapshot.gni

@@ -115,9 +115,6 @@ template("_application_snapshot") {
       "--no-link-platform",
       "--output=" + rebase_path(output),
     ]
-    if (use_nnbd) {
-      args += [ "--enable-experiment=non-nullable" ]
-    }
     if (dart_platform_bytecode) {
       args += [
         "--gen-bytecode",
@@ -150,10 +147,6 @@ template("_application_snapshot") {
                 "--snapshot-depfile=$abs_depfile",
               ] + snapshot_vm_args
 
-    if (use_nnbd) {
-      vm_args += [ "--enable-experiment=non-nullable" ]
-    }
-
     if (dart_snapshot_kind == "kernel") {
       vm_args += [ "--snapshot-kind=kernel" ]
       assert(training_args != "", "Ignoring unused argument")

utils/kernel-service/BUILD.gn

@@ -115,9 +115,6 @@ template("kernel_service_dill") {
           "--no-embed-sources",
           "--output=" + rebase_path(output),
         ]
-    if (use_nnbd) {
-      args += [ "--enable-experiment=non-nullable" ]
-    }
     args += [ scheme + ":///pkg/vm/bin/kernel_service.dart" ]
     if (dart_platform_bytecode) {
       args += [