Skip initialization of referral system for the default referral code (uplift to 1.22.x)

[brave-builds]

Uplift of #8103
Fixes brave/brave-browser#14428

Pre-approval checklist:

• You have tested your change on Nightly.
• This contains text which needs to be translated.
  • There are more than 7 days before the release.
  • I've notified folks in #l10n on Slack that translations are needed.
• The PR milestones match the branch they are landing to.

Pre-merge checklist:

• You have checked CI and the builds, lint, and tests all pass or are not related to your PR.

Post-merge checklist:

• The associated issue milestone is set to the smallest version that the changes is landed on.

[kjozwiak]

post-init failed audit-deps as per https://ci.brave.com/job/pr-brave-browser-pr8103_bsc-remove-default-promo-code_1.22.x-post-init/1/execution/node/144/log/. However, this is a known issue and doesn't block uplift.

[kjozwiak]

Uplift into 1.22.x approved after deliberating with @brave/uplift-approvers. QA has verified the PR on Nightly as per #8103 (comment) & #8103 (comment).