`<amp-font>` visual diff test is flaky

### Description

The "Fonts" visual diff test that uses the deprecated `` component is flaky ("Fonts 404" is not flaky, for what it's worth), causing the entire visual diff test runner to hang sometimes. Percy still completes the build without it, which causes the test to appear and disappear from the base build

Test disabled with PR #34793

### Reproduction Steps

e.g., it's missing from this build: https://percy.io/ampproject/amphtml/builds/10915437/missing ([CircleCI job](https://app.circleci.com/pipelines/github/ampproject/amphtml/10921/workflows/d9763739-a319-4885-9f98-8cda5b7e7aee/jobs/171871))
but present in this build: https://percy.io/ampproject/amphtml/builds/10913099 ([CircleCI job](https://app.circleci.com/pipelines/github/ampproject/amphtml/10912/workflows/6317c071-f5a3-40fa-96a9-3ab363cd9f74/jobs/171615))

### Relevant Logs

_No response_

### Browser(s) Affected

_No response_

### OS(s) Affected

_No response_

### Device(s) Affected

_No response_

### AMP Version Affected

_No response_