fix codeowners ordering (#336)

Author: SylvainJuge

.github/CODEOWNERS

@@ -1,3 +1,3 @@
+* @elastic/apm-agent-java
 /.github/actions/  @elastic/apm-agent-java @elastic/observablt-ci
 /.github/workflows/  @elastic/apm-agent-java @elastic/observablt-ci
-* @elastic/apm-agent-java