[frontend testing] Some tests exceed timeout when run locally

Run npm run test-frontend, then press a to run tests on all the files. Even though all the tests pass in our GHA workflow, running locally often results in errors like this:

Summary of all failing tests
 FAIL  src/components/WordCard/tests/SenseCard.test.tsx (29.532 s)
  ● SenseCard › has an icon for part of speech (if not GramCatGroup.Unspecified)

    thrown: "Exceeded timeout of 5000 ms for a test.
    Add a timeout value to this test to increase the timeout, if this is a long-running test. See https://jestjs.io/docs/api#testname-fn-timeout."

      35 |
      36 | describe("SenseCard", () => {
    > 37 |   it("has an icon for part of speech (if not GramCatGroup.Unspecified)", async () => {
         |   ^
      38 |     const sense = newSense("gloss");
      39 |     await renderSenseCard(sense);
      40 |     expect(() => renderer.root.findByType(PartOfSpeechButton)).toThrow();

      at it (src/components/WordCard/tests/SenseCard.test.tsx:37:3)
      at Object.describe (src/components/WordCard/tests/SenseCard.test.tsx:36:1)

 FAIL  src/components/Login/tests/Signup.test.tsx (30.165 s)
  ● Signup › submit button › errors when email blank

    thrown: "Exceeded timeout of 5000 ms for a test.
    Add a timeout value to this test to increase the timeout, if this is a long-running test. See https://jestjs.io/docs/api#testname-fn-timeout."

      92 | describe("Signup", () => {
      93 |   describe("submit button", () => {
    > 94 |     it("errors when email blank", async () => {
         |     ^
      95 |       await renderSignup();
      96 |       await typeInField(SignupId.FieldEmail, "");
      97 |       await typeInField(SignupId.FieldName, nameValid);

      at it (src/components/Login/tests/Signup.test.tsx:94:5)
      at describe (src/components/Login/tests/Signup.test.tsx:93:3)
      at Object.describe (src/components/Login/tests/Signup.test.tsx:92:1)

Run npm run test-frontend, then press a to reproduce the local failures. Start with src/components/WordCard/tests/SenseCard.test.tsx and src/components/Login/tests/Signup.test.tsx, focusing on the tests named in the timeout output. Done means the frontend test suite passes locally when all files are run.