fix(async): pass numeric value of delay timer to unrefTimer when persistent=false

[lionel-rowe]

Bug was introduced in #6775, as setArbitraryLengthTimeout returns { valueOf(): number } rather than a primitive number, and Deno.unrefTimer throws if its argument isn't a number.

Previous type checking missed it due to already using a // @ts-ignore for the offending line, and the test also missed it due to stubbing Deno.unrefTimer with a no-op.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.16%. Comparing base (91d1d55) to head (6d95f3c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6822      +/-   ##
==========================================
- Coverage   94.16%   94.16%   -0.01%     
==========================================
  Files         573      573              
  Lines       42400    42401       +1     
  Branches     6732     6732              
==========================================
- Hits        39928    39926       -2     
- Misses       2422     2424       +2     
- Partials       50       51       +1     

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[lionel-rowe]

I think (?) 368f865 should reliably fix the flaky test from this test (v1.x, macOS-latest) CI run:

delay() runs to completion with `ms` argument > 0x7fffffff => ./async/delay_test.ts:185:6
error: Leaks detected:
  - A timer was started before the test, but completed during the test. Intervals and timers should not complete in a test if they were not started in that test. This is often caused by not calling `clearTimeout`. The operation was started here:
    at Object.queueUserTimer (ext:core/01_core.js:792:9)
    at setTimeout (ext:deno_web/02_timers.js:74:15)
    at queueTimeout (file:///Users/runner/work/std/std/async/delay.ts:90:9)
    at setArbitraryLengthTimeout (file:///Users/runner/work/std/std/async/delay.ts:93:3)
    at file:///Users/runner/work/std/std/async/delay.ts:58:15
    at new Promise (<anonymous>)
    at delay (file:///Users/runner/work/std/std/async/delay.ts:49:10)
    at fn (file:///Users/runner/work/std/std/async/delay_test.ts:131:13)
    at innerWrapped (ext:cli/40_test.js:191:11)
    at exitSanitizer (ext:cli/40_test.js:107:33)