Fix styling for Request CVE button in sidebar

Resolves #343059 (closed)

What does this MR do and why?

Fix styling for "Request CVE" button in Issue Sidebar.

It was done by using a commonly used class for the sidebar (block) which makes it consistent with other sections.

Also, did a minor refactor by using helpPagePath helper method.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Apply the follow patch

diff --git a/ee/app/views/shared/issuable/_sidebar_cve_id_request.haml b/ee/app/views/shared/issuable/_sidebar_cve_id_request.haml
index 335b4dd6e1d..3323ee7a1b3 100644
--- a/ee/app/views/shared/issuable/_sidebar_cve_id_request.haml
+++ b/ee/app/views/shared/issuable/_sidebar_cve_id_request.haml
@@ -1,2 +1 @@
-- if issuable_sidebar[:request_cve_enabled_for_user]
-  #js-sidebar-cve-id-request-entry-point
+#js-sidebar-cve-id-request-entry-point
\ No newline at end of file

2. Open a confidential issue on GDK

3. Look for Request CVE button on the sidebar

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.