Clean CVE feed shortcode i18n caption data

Previsouly we were using two data items:
    ```toml
    [cve_table_date_before]
    other = "(last updated: "
    [cve_table_date_after]
    other = ")"
    ```
Which was simplified, using printf, to:
    ```toml
    [cve_table_date_format_string]
    other = "(last updated: %s)"
    ```
This is related to the following discussion
kubernetes#38579 (comment)

Author: mtardy

data/i18n/en/en.toml

@@ -55,14 +55,11 @@ other = "Issue Summary"
 [cve_table]
 other = "Official Kubernetes CVE List"
 
-[cve_table_date_before]
-other = "(last updated: "
-
 [cve_table_date_format]
 other = "02 Jan 2006 15:04:05 MST"
 
-[cve_table_date_after]
-other = ")"
+[cve_table_date_format_string]
+other = "(last updated: %s)"
 
 [deprecation_title]
 other = "You are viewing documentation for Kubernetes version:"

layouts/shortcodes/cve-feed.html

@@ -3,7 +3,7 @@
   {{ errorf "Build Failed. CVE feed does not comply with JSON feed v1.1" }}
 {{ end }}
 <table class="security-cves">
-  <caption style="caption-side: top;">{{ T "cve_table" }} {{ T "cve_table_date_before" }}{{ $feed._kubernetes_io.updated_at | time.Format ( T "cve_table_date_format" ) }}{{ T "cve_table_date_after" }}</caption>
+  <caption style="caption-side: top;">{{ T "cve_table" }} {{ printf (T "cve_table_date_format_string") ($feed._kubernetes_io.updated_at | time.Format (T "cve_table_date_format")) }}</caption>
   <thead>
   <tr>
     <th>{{ T "cve_id" }}</th>