fix(FEC-12351): cc button changed to enable during change media

[Tzipi-kaltura]

Description of the Changes

the issue:
when click on the cc button to disable caption and then occur the "change media" functionality the new video start with cc enabled.

root cause:
when turn off the caption from the cc button the previous language variable not change to off and still storing the previous language.

the solution:
the previous language viarable will be changed to off also when clicking cc button and not only when clicking "off" in the language button.

CheckLists

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• test are passing in local environment
• Travis tests are passing (or test results are not worse than on master branch :))
• Docs have been updated