Update custom homepage top site download link (uplift to 1.9.x)

[brave-builds]

Uplift of #5509
Fixes brave/brave-browser#9714

Approved, please ensure that before merging:

• You have checked CI and the builds, lint, and tests all pass or are not related to your PR.
• You have tested your change on Nightly.
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After you merge:

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

[kjozwiak]

Looks like test-browser failed on macOS as per https://ci.brave.com/job/pr-brave-browser-pr5509_fix_for_download_link_dp_1.9.x/1/execution/node/566/log/.

19:04:14  [  FAILED  ] BraveRewardsBrowserTest.NotVerifiedWallet, where TypeParam =  and GetParam() =  (6595 ms)
19:04:14  [539/539] BraveRewardsBrowserTest.NotVerifiedWallet (6875 ms)
19:04:14  1 test failed:
19:04:14      BraveRewardsBrowserTest.NotVerifiedWallet (../../brave/components/brave_rewards/browser/rewards_service_browsertest.cc:2331)

However, this is a known issue which will be fixed via brave/brave-browser#9339 and doesn't block uplift.

[srirambv]

Uplift to 1.9.x approved after deliberating with @brave/uplift-approvers .