(core) Retry flaky daily API usage test

Summary: This particular test fails often enough to be annoying but not often enough to be worrying. It's not clear why, but it seems like a race condition involving redis. Fixing the test 'properly' seems hard and not worth the effort. Looking at the past 20 Jenkins builds, I found this test failing once. If we assume that the probability of failing is 1/20 (it's probably less since the test actually runs 3 times with different server configurations) then the probability of failing 3 times independently is (1/20)^3 = 1/8000, so `this.retry(3)` seems like a good enough solution. See also: https://grist.slack.com/archives/C0234CPPXPA/p1652909955773049

Test Plan: Manually made the test fail randomly 90% of the time, in which case `this.retries(3)` was not usually enough to prevent failures, but `this.retries(300)` was.

Reviewers: paulfitz

Reviewed By: paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D3595

test/server/lib/DocApi.ts

@@ -2367,6 +2367,7 @@ function testDocApi() {
     });
 
     it("limits daily API usage and sets the correct keys in redis", async function() {
+      this.retries(3);
       // Make a new document in a free team site, currently the only real product which limits daily API usage.
       const freeTeamApi = makeUserApi('freeteam');
       const workspaceId = await getWorkspaceId(freeTeamApi, 'FreeTeamWs');