Readd dependency to fix tests

Author: nielsbauman

x-pack/qa/multi-project/core-rest-tests-with-multiple-projects/build.gradle

@@ -17,6 +17,7 @@ dependencies {
   clusterModules project(xpackModule('ilm'))
   clusterModules project(xpackModule('mapper-constant-keyword'))
   clusterModules project(xpackModule('wildcard'))
+  clusterModules project(':test:external-modules:test-multi-project')
   restTestConfig project(path: ':modules:data-streams', configuration: "basicRestSpecs")
   restTestConfig project(path: ':modules:ingest-common', configuration: "basicRestSpecs")
   restTestConfig project(path: ':modules:reindex', configuration: "basicRestSpecs")