timers: fix refreshed timers exiting too early
If a timer is refreshed in its callback, we should not decrease refCount
to prevent exiting event loop ahead of time.
Fixes: https://github.com/nodejs/node/issues/26642
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines