Re-enable serverless tests that are currently marked temporarily disabled

SERVER-67791 fixed an issue where the `requires_fcv_` tags were incorrectly still disabling tests from running even though we are currently developing 6.1. As part of that fix, several tests were marked with TEMPORARILY_DISABLED since running them resulted in failures. This ticket is to investigate whether the tests listed need to be updated to use requires_fcv_61 or there is a real multiversion bug:

• jstests/replsets/shard_merge_enabled.js
• jstests/replsets/shard_merge_invalid_options.js
• jstests/replsets/tenant_migration_advance_stable_ts_after_clone.js
• jstests/replsets/tenant_migration_buildindex_shard_merge.js
• jstests/replsets/tenant_migration_recipient_vote_imported_files.js