MonoAOTCompilerTask: Don't check for temp file if cache is disabled (#71411)

* MonoAOTCompilerTask: Don't check for temp file if cache is disabled

Prompted by #70851 (comment)

* Emit a message when deleting tmp files

Author: radical

src/tasks/AotCompilerTask/MonoAOTCompiler.cs

@@ -936,12 +936,6 @@ private bool PrecompileLibrary(PrecompileArguments args)
         bool copied = false;
         foreach (var proxyFile in args.ProxyFiles)
         {
-            if (!File.Exists(proxyFile.TempFile))
-            {
-                Log.LogError($"Precompile command succeeded, but can't find the expected temporary output file - {proxyFile.TempFile} for {assembly}.{Environment.NewLine}{output}");
-                return false;
-            }
-
             copied |= proxyFile.CopyOutputFileIfChanged();
             _fileWrites.Add(proxyFile.TargetFile);
         }
@@ -1225,11 +1219,11 @@ public bool CopyOutputFileIfChanged()
         if (!_cache.Enabled)
             return true;
 
+        if (!File.Exists(TempFile))
+            throw new LogAsErrorException($"Could not find the temporary file {TempFile} for target file {TargetFile}. Look for any errors/warnings generated earlier in the build.");
+
         try
         {
-            if (!File.Exists(TempFile))
-                throw new LogAsErrorException($"Could not find the temporary file {TempFile} for target file {TargetFile}. Look for any errors/warnings generated earlier in the build.");
-
             if (!_cache.ShouldCopy(this, out string? cause))
             {
                 _cache.Log.LogMessage(MessageImportance.Low, $"Skipping copying over {TargetFile} as the contents are unchanged");
@@ -1246,6 +1240,7 @@ public bool CopyOutputFileIfChanged()
         }
         finally
         {
+            _cache.Log.LogMessage(MessageImportance.Low, $"Deleting temp file {TempFile}");
             File.Delete(TempFile);
         }
     }