Revert workarounds for dotnet/linker#2181 (#57451)

* Revert workarounds for dotnet/linker#2181

Trying to revert both.
The Http3RequestStream is definitely fixed by the linker changes.
The ArrayPool ones probably not, but trying to get a repro.

* Fully revert ArrayPool workaround

Author: vitek-karas

src/libraries/System.Private.CoreLib/src/System/Buffers/TlsOverPerCoreLockedStacksArrayPool.cs

@@ -211,8 +211,14 @@ public bool Trim()
             // Under high pressure, release all thread locals.
             if (pressure == Utilities.MemoryPressure.High)
             {
-#if !MONO // TODO https://github.com/mono/linker/issues/2181: Remove !MONO ifdefs in this method once  is fixed
-                if (log.IsEnabled())
+                if (!log.IsEnabled())
+                {
+                    foreach (KeyValuePair<ThreadLocalArray[], object?> tlsBuckets in _allTlsBuckets)
+                    {
+                        Array.Clear(tlsBuckets.Key);
+                    }
+                }
+                else
                 {
                     foreach (KeyValuePair<ThreadLocalArray[], object?> tlsBuckets in _allTlsBuckets)
                     {
@@ -226,14 +232,6 @@ public bool Trim()
                         }
                     }
                 }
-                else
-#endif
-                {
-                    foreach (KeyValuePair<ThreadLocalArray[], object?> tlsBuckets in _allTlsBuckets)
-                    {
-                        Array.Clear(tlsBuckets.Key);
-                    }
-                }
             }
             else
             {
@@ -268,14 +266,10 @@ public bool Trim()
                         {
                             // Time noticeably wrapped, or we've surpassed the threshold.
                             // Clear out the array, and log its being trimmed if desired.
-                            if (Interlocked.Exchange(ref buckets[i].Array, null) is T[] buffer)
+                            if (Interlocked.Exchange(ref buckets[i].Array, null) is T[] buffer &&
+                                log.IsEnabled())
                             {
-#if !MONO
-                                if (log.IsEnabled())
-                                {
-                                    log.BufferTrimmed(buffer.GetHashCode(), buffer.Length, Id);
-                                }
-#endif
+                                log.BufferTrimmed(buffer.GetHashCode(), buffer.Length, Id);
                             }
                         }
                     }