[improve][test] Set diskUsageThreshold to 0.999 for tests to effectively disable the check

[lhotari]

Motivation

The shared test BookKeeper clusters used by SharedPulsarCluster and SharedMultiBrokerPulsarCluster rely on BookKeeper's default diskUsageThreshold (0.95). When a developer's local disk is more than 95% full, all bookies are flagged as read-only on startup, and tests that need writable bookies fail with the obscure error Not enough non-faulty bookies available. The disk-usage check is irrelevant to the behavior these tests are exercising, so the threshold should be effectively disabled to keep the tests environment-agnostic.

Modifications

• In SharedPulsarCluster and SharedMultiBrokerPulsarCluster, set diskUsageThreshold to 0.999 and diskUsageWarnThreshold to 0.99 on the BookKeeper server configuration so the check no longer fails tests on machines with nearly-full disks.

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment