Bug 33059: Fix capitalizatoin of AV sample category descriptions

Bug 33059: Fix capitalizatoin of AV sample category descriptions

* Fixes capitalization
* Standardizes on e-book (see https://www.oxfordlearnersdictionaries.com/definition/english/e-book)
* Standardizes on audiobook (see https://www.oxfordlearnersdictionaries.com/definition/english/audiobook)

To test:
* This is a little difficult to test. What you'd need to do:
* Apply the patch
* Drop your database, recreate it, run the web installer
* Make sure to select the optional AV along with the mandatory to install
* Log into Koha after finishing the installer and go to administration >
  authorised values
* Review the existing sample values for incorrect capitalization in
  the different categories

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 8e4d5279703be5f8e9313f2e497bfa98b58e422c)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>