fix: presubmit failure for samples backups test (#2492)

* fix: presubmit failure for samples backups test

* gemini review

Author: alkatrivedi

protos/protos.d.ts

@@ -112,10 +112,27 @@ const GAX_OPTIONS = {
   },
 };
 
-const delay = async test => {
+async function cleanupDatabase(instanceId, databaseId) {
+  const database = spanner.instance(instanceId).database(databaseId);
+  try {
+    await database.delete();
+  } catch (err) {
+    // ignore the error in case the database doesn't exists
+    if (err.code !== 5) {
+      throw err;
+    }
+  }
+}
+
+const delay = async (test, cleanupFn = null) => {
   const retries = test.currentRetry();
   // No retry on the first failure.
   if (retries === 0) return;
+
+  // run cleanup for database, provided
+  if (cleanupFn) {
+    await cleanupFn();
+  }
   // See: https://cloud.google.com/storage/docs/exponential-backoff
   const ms = Math.pow(2, retries) + Math.random() * 1000;
   return new Promise(done => {
@@ -1518,7 +1535,9 @@ describe('Autogenerated Admin Clients', () => {
     // we'll have to retry.
     this.retries(5);
     // Delay the start of the test, if this is a retry.
-    await delay(this.test);
+    await delay(this.test, async () => {
+      await cleanupDatabase(INSTANCE_ID, RESTORE_DATABASE_ID);
+    });
 
     const output = execSync(
       `${backupsCmd} restoreBackup ${INSTANCE_ID} ${RESTORE_DATABASE_ID} ${BACKUP_ID} ${PROJECT_ID}`,
@@ -1539,7 +1558,9 @@ describe('Autogenerated Admin Clients', () => {
     // we'll have to retry.
     this.retries(5);
     // Delay the start of the test, if this is a retry.
-    await delay(this.test);
+    await delay(this.test, async () => {
+      await cleanupDatabase(INSTANCE_ID, ENCRYPTED_RESTORE_DATABASE_ID);
+    });
 
     const key = await getCryptoKey(KEY_LOCATION_ID1);
 
@@ -2510,7 +2531,9 @@ describe('Autogenerated Admin Clients', () => {
       // we'll have to retry.
       this.retries(5);
       // Delay the start of the test, if this is a retry.
-      await delay(this.test);
+      await delay(this.test, async () => {
+        await cleanupDatabase(MULTI_REGION_INSTANCE_ID, MR_CMEK_RESTORED);
+      });
 
       const output = execSync(
         `node backups-restore-with-multiple-kms-keys.js \