Ignore samples folder when running clean.cmd

[NavneetThekkumpat]

Ignore samples folder when running clean.cmd

Checklist

• [x] My changes generate no new warnings
• [x] I used clear names for everything
• [x] I have performed a self-review of my own code

[github-actions[bot]]

Package	Line Rate	Branch Rate	Complexity	Health
Microsoft.PowerApps.TestEngine	91%	88%	819	✔
Summary	91% (2157 / 2380)	88% (498 / 564)	819	✔

Minimum allowed line rate is 50%