fix: best-effort dismiss of Background Payments intro sheet

[piotr-iohk]

TL;DR

Rebased onto latest main after #233 and #235. Same unique helper as #234 / #241: best-effort dismissBackgroundPaymentsTimedSheet so a missing Background Payments intro does not fail the Android send shard.

Companion app branch: fix/417-keep-lnurl-pay-comment (bitkit-android#1310).

Why

Android merge-gate E2E failed only on e2e-tests-local - send for synonymdev/bitkit-android#1310 (keep lnurl pay comment as activity note):

https://github.com/synonymdev/bitkit-android/actions/runs/35354493540

Error 3/3: element BackgroundPaymentsIntro-later still not displayed after 30000ms in dismissBackgroundPaymentsTimedSheet, called from send.e2e.ts @send_2. Product changes are unrelated. Same-named harness branch so determine-e2e-branch picks this up.

Change

Soften dismissBackgroundPaymentsTimedSheet to a waitForToastBestEffort-style poll:

• If the intro is shown, still tap Later / Cancel so remaining coverage runs on an unobstructed home.
• If the sheet is missing or auto-dismissed, log and continue instead of failing the spec.
• Use triggerTimedSheetUnlessPresent so we do not HeaderMenu-trigger over an already-visible sheet.

Conflict resolution: kept this PR’s best-effort poll; dropped main’s leftover #235 hard-wait body. Settings toast soft-wait is already on main (#233) and was not part of this PR.

Test plan

• eslint + tsc --noEmit on test/helpers/actions.ts
• Re-run Android e2e-tests-local - send on android#1310 after this rebase (no emulator in this environment)