migrate_transcripts: --all-courses now means "active courses"

[OmarIthawi]

Fixes for the following playbook: https://appsembler.atlassian.net/l/cp/d2Nim7gF

[github-actions[bot]]

Checking git merge conflicts against https://github.com/edx/edx-platform.git

Comparing with	open-release/koa.master
Benchmark conflicts with main	111
Current conflicts	111
Summary	Good work! No added conflicts.

Comparing with	open-release/lilac.master
Benchmark conflicts with main	254
Current conflicts	254
Summary	Good work! No added conflicts.

Comparing with	open-release/maple.master
Benchmark conflicts with main	285
Current conflicts	285
Summary	Good work! No added conflicts.

Comparing with	open-release/nutmeg.master
Benchmark conflicts with main	293
Current conflicts	293
Summary	Good work! No added conflicts.

Comparing with	master
Benchmark conflicts with main	291
Current conflicts	291
Summary	Good work! No added conflicts.

[coveralls]

Pull Request Test Coverage Report for Build 3111060118

• 8 of 13 (61.54%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.0005%) to 49.027%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cms/djangoapps/contentstore/management/commands/migrate_transcripts.py	4	9	44.44%
<!--	Total:	8	13	61.54%	-->

Totals
Change from base Build 3097957603:	0.0005%
Covered Lines:	110930
Relevant Lines:	226261

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💛 - Coveralls