chore(cli-repl): fix flaky autocompletion test MONGOSH-1960

Our current autocomplete logic does not always wait for the collection
or database name caches to be filled, in case it takes longer than 200ms
to do so. By ensuring that the caches are filled before we run the test,
we get consistent results.

Author: addaleax

packages/cli-repl/src/cli-repl.spec.ts

@@ -2414,6 +2414,9 @@ describe('CliRepl', function () {
 
       it('completes use <db>', async function () {
         if (!hasDatabaseNames) return;
+        input.write('db.getMongo()._listDatabases()\n'); // populate database cache
+        await waitEval(cliRepl.bus);
+
         input.write('use adm');
         await tab();
         await waitCompletion(cliRepl.bus);
@@ -2429,12 +2432,13 @@ describe('CliRepl', function () {
 
       it('completes properties of shell API result types', async function () {
         if (!hasCollectionNames) return;
+
         input.write(
           'res = db.autocompleteTestColl.deleteMany({ deletetestdummykey: 1 })\n'
         );
         await waitEval(cliRepl.bus);
 
-        // Consitency check: The result actually has a shell API type tag:
+        // Consistency check: The result actually has a shell API type tag:
         output = '';
         input.write('res[Symbol.for("@@mongosh.shellApiType")]\n');
         await waitEval(cliRepl.bus);