Upload: Expand error codes to include all 5xx HTTP errors when retrying to...

Upload: Expand error codes to include all 5xx HTTP errors when retrying to create image sub-sizes. Some servers may be configured to set HTTP 508 or 504, or possibly other `5` errors.

Porps mikeschroder, azaozz.
Fixes #48379.
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git-svn-id: https://core.svn.wordpress.org/trunk@46363 1a063a9b-81f0-0310-95a4-ce76da25c4cd