refactor(secret): move warning about file size after IsBinary check

[DmitriyLewen]

Description

Fix problem that we write warning every each binary file larger than 10MB.

Before:

➜ ./trivy fs --scanners secret ./trivy 
2024-07-09T12:19:09+06:00       INFO    Secret scanning is enabled
2024-07-09T12:19:09+06:00       INFO    If your scanning is slow, please try '--scanners vuln' to disable secret scanning
2024-07-09T12:19:09+06:00       INFO    Please see also https://aquasecurity.github.io/trivy/dev/docs/scanner/secret#recommendation for faster secret detection
2024-07-09T12:19:09+06:00       WARN    [secret] The size of the scanned file is too large. It is recommended to use `--skip-files` for this file to avoid high memory consumption.     file_path="trivy" size (MB)=240

After:

➜  ./trivy fs --scanners secret ./trivy
2024-07-09T12:21:13+06:00       INFO    Secret scanning is enabled
2024-07-09T12:21:13+06:00       INFO    If your scanning is slow, please try '--scanners vuln' to disable secret scanning
2024-07-09T12:21:13+06:00       INFO    Please see also https://aquasecurity.github.io/trivy/dev/docs/scanner/secret#recommendation for faster secret detection

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).