Make use of the new Random.Shared property (#18417)

src/Microsoft.PowerShell.Commands.Management/commands/management/Computer.cs

@@ -797,7 +797,7 @@ $result
 
             if (Wait)
             {
-                _activityId = (new Random()).Next();
+                _activityId = Random.Shared.Next();
                 if (_timeout == -1 || _timeout >= int.MaxValue / 1000)
                 {
                     _timeoutInMilliseconds = int.MaxValue;

src/System.Management.Automation/engine/hostifaces/MshHostUserInterface.cs

@@ -892,7 +892,7 @@ namespace System.Management.Automation.Host
                     {
                         // System transcripts can have high contention. Do exponential back-off on writing
                         // if needed.
-                        int delay = new Random().Next(10) + 1;
+                        int delay = Random.Shared.Next(10) + 1;
                         bool written = false;
 
                         while (!written)

src/System.Management.Automation/engine/runtime/CompiledScriptBlock.cs

@@ -1466,7 +1466,7 @@ namespace System.Management.Automation
                     // But split the segments into random sizes (10k + between 0 and 10kb extra)
                     // so that attackers can't creatively force their scripts to span well-known
                     // segments (making simple rules less reliable).
-                    int segmentSize = 10000 + (new Random()).Next(10000);
+                    int segmentSize = 10000 + Random.Shared.Next(10000);
                     int segments = (int)Math.Floor((double)(scriptBlockText.Length / segmentSize)) + 1;
                     int currentLocation = 0;
                     int currentSegmentSize = 0;

src/System.Management.Automation/help/UpdatableHelpCommandBase.cs

@@ -210,9 +210,7 @@ namespace Microsoft.PowerShell.Commands
             _exceptions = new Dictionary<string, UpdatableHelpExceptionContext>();
             _helpSystem.OnProgressChanged += HandleProgressChanged;
 
-            Random rand = new Random();
-
-            activityId = rand.Next();
+            activityId = Random.Shared.Next();
         }
 
         #endregion