[BUG] Setting#byteSizeSetting returns a fractional byte size string for the default value

[nknize]

Describe the bug
Caught on PR #9006 the RecoveryIT tests are failing due to the default value of Setting#byteSizeSetting returning fractional strings. This was introduced in #9005.

To Reproduce

./gradlew ':server:internalClusterTest' --tests "org.opensearch.indices.recovery.IndexRecoveryIT.testDoNotInfinitelyWaitForMapping" -Dtests.seed=B789E6BE668133A2 -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=nl-BE -Dtests.timezone=America/Nassau -Druntime.java=20

Expected behavior
Passing test