Redirect errors during parsing spec files into logs

Sometimes we can fall into parsing spec files silently to users, and detailed info about parsing spec files can be found in the service logs.
For example:
mock_build_srpm.log
```
RPM build errors:
error: Bad file: /builddir/build/SOURCES/negativo-nvidia.repo: No such file or directory
error: Bad file: /builddir/build/SOURCES/almalinux-nvidia.repo: No such file or directory
Bad file: /builddir/build/SOURCES/negativo-nvidia.repo: No such file or directory
Bad file: /builddir/build/SOURCES/almalinux-nvidia.repo: No such file or directory
Child return code was: 1
```
logs from journal:
```
May 26 12:42:29 builder01 python3[3780286]: error: source 0 defined multiple times
May 26 12:42:29 builder01 python3[3780286]: error: source 0 defined multiple times
```
Probably, we can somehow redirect errors via rpm binding or maybe using `contextlib.redirect_stderr` or something else