test: fix tests failing because of Editions (googleapis#2142)

* test: fix tests failing because of Editions

* fix instance partition tests

Author: rahul2393

samples/system-test/spanner.test.js

@@ -212,6 +212,7 @@ describe('Autogenerated Admin Clients', () => {
       const [, operation] = await instance.create({
         config: LOCATION_ID,
         nodes: 1,
+        edition: 'ENTERPRISE_PLUS',
         labels: {
           [LABEL]: 'true',
           created: CURRENT_TIME,
@@ -1834,6 +1835,7 @@ describe('Autogenerated Admin Clients', () => {
       const [, operation] = await instance.create({
         config: 'regional-us-central1',
         nodes: 1,
+        edition: 'ENTERPRISE_PLUS',
         displayName: 'Instance partitions test',
         labels: {
           ['cloud_spanner_samples']: 'true',