Do not create diagnostics server thread and pipe if EnableDiagnostics is set to 0 (#27137) (#27140)

* Do not create diagnostics server thread and pipe if EnableDiagnostics is set to 0

* Remove unnecessary check for config var in DiagnosticServer::Shutdown

Author: sywhang

src/inc/clrconfigvalues.h

@@ -159,7 +159,7 @@ CONFIG_DWORD_INFO_EX(INTERNAL_BreakOnUncaughtException, W("BreakOnUncaughtExcept
 
 /// Debugger
 ///
-RETAIL_CONFIG_DWORD_INFO_EX(EXTERNAL_EnableDiagnostics, W("EnableDiagnostics"), 1, "Allows the debugger and profiler diagnostics to be disabled", CLRConfig::REGUTIL_default)
+RETAIL_CONFIG_DWORD_INFO_EX(EXTERNAL_EnableDiagnostics, W("EnableDiagnostics"), 1, "Allows the debugger, profiler, and EventPipe diagnostics to be disabled", CLRConfig::REGUTIL_default)
 CONFIG_DWORD_INFO_EX(INTERNAL_D__FCE, W("D::FCE"), 0, "Allows an assert when crawling the managed stack for an exception handler", CLRConfig::REGUTIL_default)
 CONFIG_DWORD_INFO_EX(INTERNAL_DbgBreakIfLocksUnavailable, W("DbgBreakIfLocksUnavailable"), 0, "Allows an assert when the debugger can't take a lock ", CLRConfig::REGUTIL_default)
 CONFIG_DWORD_INFO_EX(INTERNAL_DbgBreakOnErr, W("DbgBreakOnErr"), 0, "Allows an assert when we get a failing hresult", CLRConfig::REGUTIL_default)

src/vm/diagnosticserver.cpp

@@ -116,6 +116,12 @@ bool DiagnosticServer::Initialize()
     }
     CONTRACTL_END;
 
+    // COMPlus_EnableDiagnostics==0 disables diagnostics so we don't create the diagnostics pipe/socket or diagnostics server thread
+    if (CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_EnableDiagnostics) == 0)
+    {
+        return true;
+    }
+
     bool fSuccess = false;
 
     EX_TRY