[server] include time index in remote log cache weight

[zuston]

Purpose

Linked issue: close #3732

The time index size is not included in the cache weight. As a result, the cache underestimates its actual storage usage and may retain more index files than allowed by remote.log.index.file.cache.size .

Brief change log

• Include both offset index and time index sizes in the remote log cache weight.
• Prevent integer overflow when converting the cache weight for Caffeine.
• Add a regression test to verify the corrected weight calculation.

Tests

API and Format

Documentation