Fixes the tag name for process tags (#3709)

* Fixes the tag name for process tags

* leftover

Author: dubloom

ext/serializer.c

@@ -1614,7 +1614,7 @@ ddog_SpanBytes *ddtrace_serialize_span_to_rust_span(ddtrace_span_data *span, ddo
     if (is_first_span) {
         zend_string *process_tags = ddtrace_process_tags_get_serialized();
         if (ZSTR_LEN(process_tags)) {
-            ddog_add_str_span_meta_zstr(rust_span, "_dd.process_tags", process_tags);
+            ddog_add_str_span_meta_zstr(rust_span, "_dd.tags.process", process_tags);
         }
     }
 

tests/Integrations/Custom/Autoloaded/ProcessTagsWebTest.php

@@ -37,8 +37,8 @@ public function testProcessTagsEnabledForWebSapi()
         $rootSpan = $traces[0][0];
 
         // Verify _dd.tags.process exists
-        $this->assertArrayHasKey('_dd.process_tags', $rootSpan['meta']);
-        $processTags = $rootSpan['meta']['_dd.process_tags'];
+        $this->assertArrayHasKey('_dd.tags.process', $rootSpan['meta']);
+        $processTags = $rootSpan['meta']['_dd.tags.process'];
 
         // Parse the process tags
         $tags = [];

tests/ext/process_tags.phpt

@@ -20,8 +20,8 @@ $child_span->service = 'test_service';
 $spans = dd_trace_serialize_closed_spans();
 
 // Check if process tags are present
-if (isset($spans[0]['meta']['_dd.process_tags'])) {
-    $processTags = $spans[0]['meta']['_dd.process_tags'];
+if (isset($spans[0]['meta']['_dd.tags.process'])) {
+    $processTags = $spans[0]['meta']['_dd.tags.process'];
     echo "Process tags present in root span: YES\n";
     echo "Process tags: $processTags\n";