test: use loss-free numbers

[pjonsson]

What this PR does

Use numbers that can be represented
in runtime without loss of precision.

This removes some no-loss-of-precision
warnings from ESLint.

Test me

This is test updates, so exercised by the test suite.

Checklist

• There are unit tests to verify my changes are correct or unit tests aren't applicable (if so, write quick reason why unit tests don't exist)
• I've updated relevant documentation in doc/.
• I've updated CHANGES.md with what I changed.
• I've provided instructions in the PR description on how to test this PR.