fix(query): allow CloudFormation DB security group /24 CIDRs

[omribz156]

Closes #7988

Reason for Proposed Changes

• The CloudFormation DB Security Group query currently treats IPv4 /24 CIDRs as larger than 256 hosts.
• A /24 has exactly 256 addresses, so it should not match the query description: "must not have more than 256 hosts."

Proposed Changes

• Update the IPv4 threshold so only prefixes smaller than /24 are reported.
• Add /24 negative fixtures for both inline and standalone CloudFormation ingress resources.
• Keep the existing /23 positive fixtures as the more-than-256-hosts coverage.

Verification

• go test ./test -run "TestQueries/cloudFormation/aws/db_security_group_open_to_large_scope" -count=1
• git diff --check (passed with local CRLF warnings only)

This was implemented with Codex assistance, with the final patch kept focused and manually reviewed.

I submit this contribution under the Apache-2.0 license.