Restore retry capture at lower resolution

The mechanism to retry capture at a lower resolution on error was
removed in favor of using video encoder capabilities instead.

However, an encoder configuration that is compatible with the declared
capabilities may still fail, either because the declared capabilities
are incorrect or because some resources are unavailable.

Restore the downsize-on-error behavior for such cases.

This reverts commit 4f97e2e30b9b02ff43d64e940165acafd7512a23.

Refs #2947 <https://github.com/Genymobile/scrcpy/pull/2947>
Refs #6766 <https://github.com/Genymobile/scrcpy/pull/6766>
PR #6822 <https://github.com/Genymobile/scrcpy/pull/6822>