fix(ci): fix Trivy grep reading wrong stdin in scan scripts

[mdryaan]

Description

Both base-image-critical.sh and binary-image-critical.sh used a while read -r line loop that redirected the scan file to the loop's stdin. Inside the loop, grep -o "CRITICAL: [0-9]*" received no file argument, so it consumed from that same shared stdin — not from $line, which was never passed to it. The CRITICAL summary was consumed by read on the first iteration; grep saw nothing and returned empty. $sum was always 0 and the security gate never triggered regardless of actual CVE counts.

Fixed by removing the while read loop entirely and passing the scan file directly to grep as a file argument. All matches are captured in one pass; the
existing for i in $x loop sums them correctly.

Fixes #394

How Has This Been Tested?

• Created /tmp/final.txt containing CRITICAL: 5, HIGH: 12, MEDIUM: 3, LOW: 1
• Old code: base image critical value is 0 — gate does not fire (bug confirmed)
• Fixed script: base image critical value is 5 + CRITICAL vulnerabilities found + Exit code: 1 — gate fires correctly (fix verified)

- The before line: OLD: base image critical value is 0 (expected 5)

- The after lines: base image critical value is 5 + CRITICAL vulnerabilities found + Exit code: 1

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates? — No.
• I've updated documentation as required by this PR.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas. — N/A.
• I have tested it for all user roles. — N/A (CI script change).
• I have added all the required unit test cases.

Does this PR introduce a breaking change for other components like worker-operator?

No

Fix Trivy CRITICAL vulnerability scan always reporting 0 — grep now reads the scan file directly instead of consuming the wrong stdin