Revert "Add MCP proxy server support for prompts"

This reverts commit ebd7310.

Author: adwsingh

mcp/mcp-server/src/main/java/software/amazon/smithy/java/mcp/server/McpService.java

@@ -220,19 +220,8 @@ private JsonRpcResponse handleInitialize(JsonRpcRequest req) {
     }
 
     private JsonRpcResponse handlePromptsList(JsonRpcRequest req) {
-        var allPrompts = new ArrayList<>(prompts.values().stream().map(Prompt::promptInfo).toList());
-
-        // Add prompts from proxy servers
-        for (McpServerProxy proxy : proxies.values()) {
-            var response = proxy.rpc(req).join();
-            if (response.getError() == null) {
-                var proxyPrompts = response.getResult().asShape(ListPromptsResult.builder()).getPrompts();
-                allPrompts.addAll(proxyPrompts);
-            }
-        }
-
         var result = ListPromptsResult.builder()
-                .prompts(allPrompts)
+                .prompts(prompts.values().stream().map(Prompt::promptInfo).toList())
                 .build();
         return createSuccessResponse(req.getId(), result);
     }
@@ -243,12 +232,12 @@ private JsonRpcResponse handlePromptsGet(JsonRpcRequest req) {
 
         var prompt = prompts.get(normalize(promptName));
 
-        if (prompt != null) {
-            var result = promptProcessor.buildPromptResult(prompt, promptArguments);
-            return createSuccessResponse(req.getId(), result);
+        if (prompt == null) {
+            throw new RuntimeException("Prompt not found: " + promptName);
         }
 
-        throw new RuntimeException("Prompt not found: " + promptName);
+        var result = promptProcessor.buildPromptResult(prompt, promptArguments);
+        return createSuccessResponse(req.getId(), result);
     }
 
     private JsonRpcResponse handleToolsList(JsonRpcRequest req, ProtocolVersion protocolVersion) {