Re-enable jemalloc's background thread by default (#9813)

[ti-chi-bot]

This is an automated cherry-pick of #9813

What problem does this PR solve?

Issue Number: close #9812 ref #9722

Problem Summary:

See issue 9812

What is changed and how it works?

Re-enable jemalloc's background thread by default

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix an issue that the memory may stay in high level after large amount of data ingested

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, Lloyd-Pottiger

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• OWNERS [JaySon-Huang,Lloyd-Pottiger]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-01-22 13:01:12.307091314 +0000 UTC m=+272199.638010719: ☑️ agreed by JaySon-Huang.
• 2025-01-23 01:39:19.607306567 +0000 UTC m=+317686.938225971: ☑️ agreed by Lloyd-Pottiger.