[MetricsAdvisor] Flaky tests: too many requests

[kinelski]

We've been constantly getting 429 (Too Many Requests) errors back from the service in the last couple of weeks.

Example: https://dev.azure.com/azure-sdk/internal/_build/results?buildId=852151&view=logs&j=3b626316-2910-5c8d-5d81-481f945c5c1a&t=9c88e125-f222-512d-2767-31294fe58e36&l=679

2021-04-20T13:08:37.0024794Z   Failed UpdateMySqlDataFeedWithMinimumSetupAndNewInstance [20 s]
2021-04-20T13:08:37.0028010Z   Error Message:
2021-04-20T13:08:37.0033426Z    Azure.RequestFailedException : Requests to the Get a data feed by its id Operation under Metrics Advisor have exceeded rate limit of your current MetricsAdvisor S0 pricing tier. Please retry after 1 second. Please contact Azure support service if you would like to further increase the default rate limit.
2021-04-20T13:08:37.0035994Z Status: 429 (Too Many Requests)
2021-04-20T13:08:37.0037415Z ErrorCode: 429
2021-04-20T13:08:37.0038093Z 
2021-04-20T13:08:37.0039423Z Content:
2021-04-20T13:08:37.0041474Z {"error":{"code":"429","message": "Requests to the Get a data feed by its id Operation under Metrics Advisor have exceeded rate limit of your current MetricsAdvisor S0 pricing tier. Please retry after 1 second. Please contact Azure support service if you would like to further increase the default rate limit."}}
2021-04-20T13:08:37.0042878Z 
2021-04-20T13:08:37.0044283Z Headers:
2021-04-20T13:08:37.0045886Z Retry-After: 1
2021-04-20T13:08:37.0048875Z apim-request-id: REDACTED
2021-04-20T13:08:37.0050281Z Strict-Transport-Security: REDACTED
2021-04-20T13:08:37.0051723Z X-Content-Type-Options: REDACTED
2021-04-20T13:08:37.0053057Z Date: Tue, 20 Apr 2021 13:08:35 GMT
2021-04-20T13:08:37.0054439Z Content-Length: 312
2021-04-20T13:08:37.0055814Z Content-Type: application/json

Currently there are no other pricing tiers to choose from, so consider writing a mechanism to ignore these types of failures in our test infrastructure.