test_runner: enhance #handleEvent to handle levels

Updated to process the parameter for events. Messages
are now formatted with colors based on the
(e.g., 'info', 'warn', 'error').
This change ensures diagnostic messages are visually distinct,
improving clarity and reducing debugging effort during test runs.

Refs: nodejs#55922

lib/internal/test_runner/reporter/spec.js

@@ -69,8 +69,10 @@ class SpecReporter extends Transform {
       case 'test:stderr':
       case 'test:stdout':
         return data.message;
-      case 'test:diagnostic':
-        return `${reporterColorMap[type]}${indent(data.nesting)}${reporterUnicodeSymbolMap[type]}${data.message}${colors.white}\n`;
+      case 'test:diagnostic':{
+        const diagnosticColor = reporterColorMap[data.level] || reporterColorMap['test:diagnostic'];
+        return `${diagnosticColor}${indent(data.nesting)}${reporterUnicodeSymbolMap[type]}${data.message}${colors.white}\n`;
+      }
       case 'test:coverage':
         return getCoverageReport(indent(data.nesting), data.summary,
                                  reporterUnicodeSymbolMap['test:coverage'], colors.blue, true);