add codeowners for legacy server folder (#52158)

.github/CODEOWNERS

@@ -5,6 +5,7 @@
 # App
 /x-pack/legacy/plugins/lens/ @elastic/kibana-app
 /x-pack/legacy/plugins/graph/ @elastic/kibana-app
+/src/legacy/server/sample_data/ @elastic/kibana-app
 
 # App Architecture
 /src/plugins/data/ @elastic/kibana-app-arch
@@ -66,14 +67,25 @@
 /packages/kbn-es/ @elastic/kibana-operations
 /packages/kbn-pm/ @elastic/kibana-operations
 /packages/kbn-test/ @elastic/kibana-operations
+/src/legacy/server/keystore/ @elastic/kibana-operations
+/src/legacy/server/pid/ @elastic/kibana-operations
+/src/legacy/server/sass/ @elastic/kibana-operations
+/src/legacy/server/utils/ @elastic/kibana-operations
+/src/legacy/server/warnings/ @elastic/kibana-operations
 
 # Platform
 /src/core/  @elastic/kibana-platform
-/src/legacy/server/saved_objects/  @elastic/kibana-platform
 /config/kibana.yml @elastic/kibana-platform
 /x-pack/plugins/features/  @elastic/kibana-platform
 /x-pack/plugins/licensing/  @elastic/kibana-platform
 /packages/kbn-config-schema/ @elastic/kibana-platform
+/src/legacy/server/config/ @elastic/kibana-platform
+/src/legacy/server/csp/ @elastic/kibana-platform
+/src/legacy/server/http/ @elastic/kibana-platform
+/src/legacy/server/i18n/ @elastic/kibana-platform
+/src/legacy/server/logging/ @elastic/kibana-platform
+/src/legacy/server/saved_objects/  @elastic/kibana-platform
+/src/legacy/server/status/ @elastic/kibana-platform
 
 # Security
 /x-pack/legacy/plugins/security/  @elastic/kibana-security