feat(telemetry): initialize EventSource in Enable method

Author: BenjaminAbt

src/HttpUserAgentParser.MemoryCache/Telemetry/HttpUserAgentParserMemoryCacheTelemetry.cs

@@ -52,7 +52,11 @@ public static bool IsCacheSizeEnabled
     /// <summary>
     /// Enables EventCounter telemetry for the MemoryCache provider.
     /// </summary>
-    public static void Enable() => Interlocked.Or(ref s_enabledFlags, EventCountersFlag);
+    public static void Enable()
+    {
+        _ = HttpUserAgentParserMemoryCacheEventSource.Log;
+        Interlocked.Or(ref s_enabledFlags, EventCountersFlag);
+    }
 
     /// <summary>
     /// Enables native System.Diagnostics.Metrics telemetry for the MemoryCache provider.

src/HttpUserAgentParser/Telemetry/HttpUserAgentParserTelemetry.cs

@@ -60,7 +60,11 @@ public static bool IsCacheSizeEnabled
     /// <summary>
     /// Enables core EventCounter telemetry for the parser.
     /// </summary>
-    public static void Enable() => Interlocked.Or(ref s_enabledFlags, EventCountersFlag);
+    public static void Enable()
+    {
+        _ = HttpUserAgentParserEventSource.Log;
+        Interlocked.Or(ref s_enabledFlags, EventCountersFlag);
+    }
 
     /// <summary>
     /// Enables native System.Diagnostics.Metrics telemetry for the parser.