Replace graphics on RE onboarding (uplift to 1.20.x)

[brave-builds]

Uplift of #7766
Resolves brave/brave-browser#13749

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.
• The PR milestones match the branch they are landing to.

After you merge:

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

[kjozwiak]

iOS failed due to build failing as per https://ci.brave.com/job/pr-brave-browser-pr7766_issue_13749_1.20.x-ios/1/execution/node/137/log/. However, this change is isolated to Android so there's no need to restart/pass iOS. Other platforms including iOS were also skipped via the 1.19.x uplift as per #7773.

21:07:29  [9324/19802] ACTION //brave/vendor/brave-ios:ads_mojo_gen_wrappers(//build/toolchain/mac:ios_clang_arm64)
21:07:29  FAILED: gen/brave/vendor/brave-ios/ads.mojom.objc.h gen/brave/vendor/brave-ios/ads.mojom.objc+private.h gen/brave/vendor/brave-ios/ads.mojom.objc.mm gen/brave/vendor/brave-ios/objc_templates_bytecode/ads_objc_templates.zip 

[kjozwiak]

Uplift into 1.20.x approved after deliberating with @brave/uplift-approvers. QA has verified the PR on Nightly as per #7766 (comment).