REST: Test: Fix the accept_enterprise parameter for Get License API (…

…#51527)

The Get License API specifies the `accept_enterprise` parameter as a `boolean`:

https://github.com/elastic/elasticsearch/blob/0ca5cb8cb636a4be9c36b8e38e565af66abc423b/x-pack/plugin/src/test/resources/rest-api-spec/api/license.get.json#L22-L27

In the test, a `string` is passed however, which makes the test compilation fail in the Go client.

(cherry picked from commit e2a2169)

x-pack/plugin/src/test/resources/rest-api-spec/test/license/30_enterprise_license.yml

@@ -29,7 +29,7 @@ teardown:
 
   - do:
       license.get:
-        accept_enterprise: "true"
+        accept_enterprise: true
 
   ## a v5 license object has 12 attributes
   - length: { license: 12 }
@@ -41,7 +41,7 @@ teardown:
 
   - do:
       license.get:
-        accept_enterprise: "false"
+        accept_enterprise: false
 
   ## a v4 license object has 11 attributes
   - length: { license: 11 }