Removed support for mixed http/https mode

refs: https://github.com/TryGhost/Ghost/issues/14446

- currently ghost will upgrade configured urls to https if a secure request comes into a http configured site
- we no longer want to support this feature
- instead, ghost will strictly honour the configured URL

ghost/config-url-helpers/lib/config-url-helpers.js

@@ -27,16 +27,11 @@ function getSubdir() {
  * Imagine Ghost runs with http, but nginx allows SSL connections.
  *
  * @callback getSiteUrlFn
- * @param {boolean} [secure] optionally force the url to be secure
  * @return {string} returns the url as defined in config, but always with a trailing `/`
  */
-function getSiteUrl(secure = false) {
+function getSiteUrl() {
     let siteUrl = this.get('url');
 
-    if (secure) {
-        siteUrl = siteUrl.replace('http://', 'https://');
-    }
-
     if (!siteUrl.match(/\/$/)) {
         siteUrl += '/';
     }

ghost/config-url-helpers/test/config-url-helpers.test.js

@@ -72,12 +72,6 @@ describe('Config URL Helpers', function () {
 
             nconf.getSiteUrl().should.eql('http://example.com/');
         });
-
-        it('returns https if secure=true', function () {
-            fakeConfig.url = 'http://example.com/';
-
-            nconf.getSiteUrl(true).should.eql('https://example.com/');
-        });
     });
 
     describe('getAdminUrl', function () {