[BUG] MCP rule removal can leave custom-named tools registered

### Current Behavior

MCP tool registration and removal use different names when the rule handle defines a custom tool name.

During registration, `handlerRule()` prefers the tool name from the rule handle and only falls back to the rule name:

```java
shenyuMcpServerManager.addTool(server.getPath(),
StringUtils.isBlank(mcpServerTool.getName()) ? ruleData.getName() : mcpServerTool.getName(),
...);
```

During removal, `removeRule()` always removes by `ruleData.getName()`:

```java
shenyuMcpServerManager.removeTool(server.getPath(), ruleData.getName());
```

If `mcpServerTool.getName()` differs from `ruleData.getName()`, deleting or updating the rule removes the cache entry but leaves the live MCP server tool registered under the custom name.

### Expected Behavior

Rule removal should remove the same tool name that was used during registration.

### Impact

Renamed/custom-named MCP tools can remain callable after the backing rule is removed or updated, leaving stale tool definitions in the live MCP server.

### Code Location

- `shenyu-plugin/shenyu-plugin-mcp-server/src/main/java/org/apache/shenyu/plugin/mcp/server/handler/McpServerPluginDataHandler.java`
- `handlerRule()` registers by handle tool name when present.
- `removeRule()` removes only by `ruleData.getName()`.

Read shenyu-plugin/shenyu-plugin-mcp-server/src/main/java/org/apache/shenyu/plugin/mcp/server/handler/McpServerPluginDataHandler.java, focusing first on handlerRule() and removeRule(). Trace how custom and fallback tool names are selected, then verify the relevant MCP registration and removal behavior for rule deletion and updates. Done means a custom-named tool is no longer left registered after its rule is removed or updated.

Written by the indexing model from the issue text.