Fix the command execution by runner.py

[vajdera]

When no --force-check option is specified when using the runner.py the argument list for running bandersnatch command consists of '' at the end which breaks the bandersnatch command execution: bandersnatch: error: unrecognized arguments:. This commit fixes this by only appending the "--force-check" argument if specified in runner.py call.

Closes #1754

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.40%. Comparing base (4d020e8) to head (abd0db5). Report is 112 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1753 +/- ## ========================================== + Coverage 79.69% 83.40% +3.71% ========================================== Files 31 33 +2 Lines 4324 4381 +57 Branches 780 783 +3 ========================================== + Hits 3446 3654 +208 + Misses 721 537 -184 - Partials 157 190 +33 ```

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