fix: Change scope of dependencies in generated tests

After this change this library needs to be referenced with `integrationTestImplementation testFixtures('org.grails.plugins:geb')`
but now we are not leaking any test dependencies to downstream projects non-test configurations.

build.gradle

@@ -34,13 +34,10 @@ dependencies {
     compileOnly "org.grails:grails-core:$grailsVersion" // Provided as this is a Grails plugin
     compileOnly "jakarta.servlet:jakarta.servlet-api:$servletApiVersion" // Provided by the servlet container
 
-    // These are used transitively by the tests generated by the 'create-functional-test' script
-    // If they are not included as api, the generated tests will not compile without adding the dependencies manually
-    api "org.gebish:geb-spock:$gebSpock"
-    api "org.grails:grails-testing-support:$testingSupportVersion"
-    api "org.grails:grails-datastore-gorm:$datastoreVersion"
-
     testFixturesCompileOnly "jakarta.servlet:jakarta.servlet-api:$servletApiVersion"
+    testFixturesApi "org.gebish:geb-spock:$gebSpock"
+    testFixturesApi "org.grails:grails-testing-support:$testingSupportVersion"
+    testFixturesApi "org.grails:grails-datastore-gorm:$datastoreVersion"
     testFixturesApi "org.testcontainers:selenium:$testcontainersVersion"
     testFixturesApi "org.seleniumhq.selenium:selenium-chrome-driver:$seleniumVersion"
     testFixturesApi "org.seleniumhq.selenium:selenium-remote-driver:$seleniumVersion"