Remove the leftover temporary report file in BidManager download (#67076)

GoogleBidManagerDownloadReportOperator downloads the report to a
NamedTemporaryFile(delete=False) and never removes it after the GCS
upload, leaving a copy of the unencrypted report on the worker disk for
every execution.

Wrap the download+upload in try/finally so the local temp file is
deleted on both the success and failure path. The handle is closed
before the unlink so the cleanup works on Windows too (NamedTemporaryFile
keeps the handle open; unlink raises PermissionError while it is held).
Unexpected OSErrors on cleanup are surfaced as a log.warning rather than
silently swallowed, so antivirus/NFS edge cases remain observable;
FileNotFoundError stays silent because a missing file is benign.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>