Enable ci_scoped_job_token by default

What does this MR do?

Related to #332272 (closed)

In this MR we:

• enable the feature flag ci_scoped_job_token by default - This will start tracking authentications via from CI_JOB_TOKEN and will use the Ci::JobToken::Scope to validate permissions.
• enable the project setting job_token_scope_enabled by default - When enabled we only allow projects in the job token scope to be accessible, otherwise all projects are accessible as long as the job user has access to.
• fix any specs that were temporarily changed while we disabled the job_token_scope_enabled in !64962 (merged)

Database migration

rails db:migrate:redo VERSION=20210709132707

== 20210709132707 ChangeDefaultJobTokenScopeEnabled: reverting ================
-- change_column_default(:project_ci_cd_settings, :job_token_scope_enabled, {:from=>true, :to=>false})
   -> 0.0036s
== 20210709132707 ChangeDefaultJobTokenScopeEnabled: reverted (0.0123s) =======

== 20210709132707 ChangeDefaultJobTokenScopeEnabled: migrating ================
-- change_column_default(:project_ci_cd_settings, :job_token_scope_enabled, {:from=>false, :to=>true})
   -> 0.0101s
== 20210709132707 ChangeDefaultJobTokenScopeEnabled: migrated (0.0163s) =======

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• This change is backwards compatible across updates, or this does not apply.

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