fix: improve 503 handling for json resumable queries

[sfc-gh-mwnukowski]

This is exactly the same as #2289 - seem like a duplicated code that diverged.

Fixes a rare 503 handling issue

...
caused by NullPointerException: Cannot invoke "String.toLowerCase(java.util.Locale)" because the return value of "com.google.api.client.http.HttpResponseException.getContent()" is null
...
com.google.cloud.storage.JsonResumableSessionQueryTask.call(JsonResumableSessionQueryTask.java:117)
com.google.cloud.storage.JsonResumableSession.query(JsonResumableSession.java:57)

caused by StorageException: Unknown Error
	|> PUT https://storage.googleapis.com/upload/storage/v1/b/gcpeuropewest4-gcpeuropewest3-e942/o?name=<...>
	|> content-range: bytes */*
	|> x-goog-gcs-idempotency-token: <...>
	|  
	|< HTTP/1.1 503 Service Unavailable
	|< content-length: 0
	|< content-type: text/plain; charset=utf-8
	|< x-guploader-uploadid: <...>
	|  

cc @BenWhitehead

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[BenWhitehead]

Hi @sfc-gh-mwnukowski, thanks for opening this PR. A similar PR was opened as well, except that one has a test added along with it #2987

I'm going to close out this PR without merging, however I'm going to add you as a co-author on the other PR.