Automatic merge from submit-queue (batch tested with PRs 50255, 50885)
AWS: Arbitrarily choose first (lexicographically) subnet in AZ
When there is more than one subnet for an AZ on AWS choose arbitrarily
chose the first one lexicographically for consistency.
**What this PR does / why we need it**:
If two subnets were to be used appear in the same aws az which one is chosen is currently not consistent. This could lead to difficulty in diagnosing issues.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#45983
**Special notes for your reviewer**:
**Release note**:
```release-note
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c573d8192f