Fix data stream wildcard resolution bug in eql search api.(elastic#61910)

Backport of elastic#61904 to 7.x branch.

The eql search api redirects to the search api. For this reason the eql
search api could work with concrete data stream names. However if security
is enabled and a data stream name snippet with a wildcard was used then
it could not resolve this expressions. This is because the EqlSearchRequest
class didn't overwrite the `includeDataStreams()` method. This pr fixes this,
so that the security layer can properly expand data stream name wildcard
expressions for the eql search api.

This commit also moves the eql data stream test to xpack rest tests,
so that the test runs with security enabled. This is required to reproduce
the bug.

Closes elastic#60828

Author: martijnvg

x-pack/plugin/eql/qa/rest/src/yamlRestTest/resources/rest-api-spec/test/eql/20_data_streams.yml

@@ -375,6 +375,11 @@ public Task createTask(long id, String type, String action, TaskId parentTaskId,
         return new EqlSearchTask(id, type, action, getDescription(), parentTaskId, headers, null, null, keepAlive);
     }
 
+    @Override
+    public boolean includeDataStreams() {
+        return true;
+    }
+
     @Override
     public String getDescription() {
         StringBuilder sb = new StringBuilder();

x-pack/plugin/eql/src/main/java/org/elasticsearch/xpack/eql/action/EqlSearchRequest.java

@@ -474,3 +474,67 @@
       indices.delete_data_stream:
         name: simple-data-stream1
   - is_true: acknowledged
+
+---
+"Verify data stream resolvability in EQL search API":
+  - skip:
+      version: " - 7.9.99"
+      reason: "change to 7.9.1 after backport"
+      features: allowed_warnings
+
+  - do:
+      allowed_warnings:
+        - "index template [my-template1] has index patterns [simple-data-stream1] matching patterns from existing older templates [global] with patterns (global => [*]); this template [my-template1] will take precedence during new index creation"
+      indices.put_index_template:
+        name: my-template1
+        body:
+          index_patterns: [simple-data-stream1]
+          template:
+            mappings:
+              properties:
+                '@timestamp':
+                  type: date
+          data_stream: {}
+
+  - do:
+      indices.create_data_stream:
+        name: simple-data-stream1
+
+  - do:
+      bulk:
+        refresh: true
+        body:
+          - create:
+              _index: simple-data-stream1
+              _id:    1
+          - event:
+              - category: process
+            "@timestamp": 2020-02-03T12:34:56Z
+            user: SYSTEM
+
+  - do:
+      eql.search:
+        index: simple-data-stream1
+        body:
+          query: "process where user = 'SYSTEM'"
+
+  - match: {timed_out: false}
+  - match: {hits.total.value: 1}
+  - match: {hits.total.relation: "eq"}
+  - match: {hits.events.0._source.user: "SYSTEM"}
+
+  - do:
+      eql.search:
+        index: simple-data-s*
+        body:
+          query: "process where user = 'SYSTEM'"
+
+  - match: {timed_out: false}
+  - match: {hits.total.value: 1}
+  - match: {hits.total.relation: "eq"}
+  - match: {hits.events.0._source.user: "SYSTEM"}
+
+  - do:
+      indices.delete_data_stream:
+        name: simple-data-stream1
+  - is_true: acknowledged