fix(ff): stop gap for setInputFiles race

[pavelfeldman]

#29683

[github-actions]

Test results for "tests 1"

12 flaky

⚠️ [chromium] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [chromium] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [chromium] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [firefox] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [firefox] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [chromium] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [webkit] › library/browsercontext-basic.spec.ts:79:3 › should isolate localStorage and cookies @smoke
⚠️ [webkit] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks

26582 passed, 613 skipped
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