Fix mismatch between legacy events and CloudEvents in two test cases (#52)

There were source/resource mismatches in the firebase-db3 and
firebase-dbdelete2 test cases. Tests that convert between legacy events
and CloudEvents fail because the input and output source/resource
didn't match.

Author: mtraver

events/events_data.go

@@ -1,7 +1,7 @@
 {
   "eventType": "providers/google.firebase.database/eventTypes/ref.write",
   "params": {
-    "child": "abc"
+    "child": "xyz"
   },
   "auth": {
     "admin": true
@@ -10,7 +10,7 @@
     "data": null,
     "delta": 10
   },
-  "resource": "projects/_/instances/my-project-id/refs/gcf-test/abc",
+  "resource": "projects/_/instances/my-project-id/refs/gcf-test/xyz",
   "timestamp": "2020-09-29T11:32:00.000Z",
   "eventId": "aaaaaa-1111-bbbb-2222-cccccccccccc"
 }

events/generate/data/firebase-db3-legacy-input.json

@@ -1,7 +1,7 @@
 {
   "eventType": "providers/google.firebase.database/eventTypes/ref.delete",
   "params": {
-    "child": "abc"
+    "child": "xyz"
   },
   "auth": {
     "admin": true
@@ -10,7 +10,7 @@
     "data": 10,
     "delta": null
   },
-  "resource": "projects/_/instances/my-project-id/refs/gcf-test/abc",
+  "resource": "projects/_/instances/my-project-id/refs/gcf-test/xyz",
   "timestamp": "2020-09-29T11:32:00.000Z",
   "eventId": "aaaaaa-1111-bbbb-2222-cccccccccccc"
 }

events/generate/data/firebase-dbdelete2-legacy-input.json

@@ -4,7 +4,7 @@
     "delta": null
   },
   "context": {
-    "resource": "projects/_/instances/my-project-id/refs/gcf-test/abc",
+    "resource": "projects/_/instances/my-project-id/refs/gcf-test/xyz",
     "timestamp": "2020-09-29T11:32:00.000Z",
     "eventType": "providers/google.firebase.database/eventTypes/ref.delete",
     "eventId": "aaaaaa-1111-bbbb-2222-cccccccccccc"