Change Allowlist in Ruleset config

What does this MR do?

This MR related to gitlab-org/gitlab#560147 (closed) where the solution requires adding .git directory to the allowlist. In addition, there are several files and directories that are supposed to be allowlisted due to their characteristics but they are not. This could potentially add to larger scan times.

Overall, the MR changes include the following:

• allowlist is deprecated and replaced by allowlists in 8.21.0 (see config). This MR renames it in the ruleset config
• Add a set of standard files and directories in the allowlist which are non-text based files, generated files, or not related to user source code like external dependencies.
• Also, includes .git directory in the allowlist

What are the relevant issue numbers?

Investigate and Fix Secrets CI Analyzer scannin... (gitlab-org/gitlab#560147 - closed)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests updated/added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer