fix(shell-api): make db.stats() return stats for current db MONGOSH-555 (#585)

Author: addaleax

packages/shell-api/src/database.spec.ts

@@ -1691,7 +1691,7 @@ describe('Database', () => {
         await database.stats(1);
 
         expect(serviceProvider.runCommandWithCheck).to.have.been.calledWith(
-          ADMIN_DB,
+          database._name,
           {
             dbStats: 1,
             scale: 1
@@ -1703,7 +1703,7 @@ describe('Database', () => {
         await database.stats();
 
         expect(serviceProvider.runCommandWithCheck).to.have.been.calledWith(
-          ADMIN_DB,
+          database._name,
           {
             dbStats: 1,
             scale: 1

packages/shell-api/src/database.ts

@@ -825,7 +825,7 @@ export default class Database extends ShellApiClass {
   @returnsPromise
   async stats(scale = 1): Promise<Document> {
     this._emitDatabaseApiCall('stats', { scale: scale });
-    return await this._runAdminCommand(
+    return await this._runCommand(
       {
         dbStats: 1,
         scale: scale