Remove kNoSandbox now that services/service_manager/standalone is gone

Driven-by clean up past [1], where the only user of this switch was
(re)moved.

[1] https://codereview.chromium.org/2573283002

BUG=

Review-Url: https://codereview.chromium.org/2619773003
Cr-Commit-Position: refs/heads/master@{#442986}

services/service_manager/switches.cc

@@ -10,8 +10,5 @@ namespace switches {
 // Enable the tracing service.
 const char kEnableTracing[] = "enable-service-manager-tracing";
 
-// Disables the sandbox for debugging.
-const char kNoSandbox[] = "no-sandbox";
-
 }  // namespace switches
 }  // namespace service_manager

services/service_manager/switches.h

@@ -11,7 +11,6 @@ namespace switches {
 // All switches in alphabetical order. The switches should be documented
 // alongside the definition of their values in the .cc file.
 extern const char kEnableTracing[];
-extern const char kNoSandbox[];
 
 }  // namespace switches
 }  // namespace service_manager