test: increase coverage for assertion_error.js
Add a test for long strings and assert.notDeepEqual() to cover code that truncates output when it is longer than 1024 characters.
This introduces coverage for https://coverage.nodejs.org/coverage-0a4c69a5c5e8ba93/lib/internal/assert/assertion_error.js.html#L370.
I standardized nearby arrow functions to use braces when they are not intended to return a value.
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines