[Feature flag] Remove secure_security_and_compliance_configuration_page_on_ce flag

What

Remove the :secure_security_and_compliance_configuration_page_on_ce feature flag, enabled by default by #294076 (closed).

Owners

• Team: groupstatic analysis
• Most appropriate slack channel to reach out to: #s_secure-frontend
• Best individual to reach out to: @markrian or @jannik_lehmann

Roll Out Steps

• Remove feature flag and add changelog entry
• Remove relevant code branches/tests
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel