[Backport release-3_34] Fix loading of raster styles if the layer/table name is not in the datasource url

[qgis-bot]

Backport #57333
Authored by: @mhugent

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

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[github-actions]

While we hate to see this happen, this PR has been automatically closed because it has not had any activity in the last 21 days. If this pull request should be reconsidered, please follow the guidelines in the previous comment and reopen this pull request. Or, if you have any further questions, just ask! We love to help, and if there's anything the QGIS project can do to help push this PR forward please let us know how we can assist.

[manisandro]

LGTM