Bug 27422: YouTube videos are HTTPS only

Bug 27422: YouTube videos are HTTPS only

This patch hardcodes HTTPS as the protocol to use when generating
YouTube content embedding. It is the supported protocol and without this
patch it falls back to 'http', or it can be 'ftp' depending on the first
indicator of the 856 field. They are all not supported so hardcoding it.

To test:
1. Have a record with 856 $uhttps://youtu.be/sMNkDPFycNU
2. Enable the HTML5MediaYouTube and HTML5Media sysprefs
3. Open the OPAC detailed view of the record
4. Open the Multimedia tab
=> FAIL: There's no embedded video
5. Apply this patch
6. Restart all
7. Repeat 4
=> SUCCESS: There's a live performance of Heroes del Silencio!
8. Sign off :-D

Sponsored-by: Banco Central de la República Argentina
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>