Fix blacklisted_paths can not work on scan image feature

[Ethonwu]

Hi, I try to use blacklisted_paths to ignore some dir when using image scan, but it not work.

In IsSkippableDir function, use path var to compare with skippablePathIndicator var that read from blacklisted_paths, I try to print path to I get some path problem.

For example:
If I want to ignore /bin path, code will compare both two string by use HasPrefix
But in image scan feature, path output is like this: /tmp/Deepfence/SecretScanning/df_demoimage4/ExtractedFiles/<layer_id>/bin
This is reason that I this blacklisted_paths not work
So I try use TrimPrefix to let path like this:
Original
/tmp/Deepfence/SecretScanning/df_demoimage4/ExtractedFiles/<layer_id>/bin
After TrimPrefix
/bin
It will work on IsSkippableDir function, and can successful ignore blacklisted_paths by use image scan

[ramanan-ravi]

@Ethonwu Thanks for the contribution