add gateway.yml to avoid unnecessary errors (#3426)

oap-server/server-starter/pom.xml

@@ -240,6 +240,7 @@
                         <exclude>datasource-settings.properties</exclude>
                         <exclude>endpoint_naming_rules.properties</exclude>
                         <exclude>official_analysis.oal</exclude>
+                        <exclude>gateways.yml</exclude>
                     </excludes>
                 </configuration>
             </plugin>

oap-server/server-starter/src/main/assembly/assembly.xml

@@ -40,6 +40,7 @@
                 <include>alarm-settings.yml</include>
                 <include>alarm-settings-sample.yml</include>
                 <include>datasource-settings.properties</include>
+                <include>gateways.yml</include>
             </includes>
         </fileSet>
         <fileSet>