fix(slow_query): fix download slowlog api, add range preview and timezone reminder

[elleryasimov]

• Fix slowquery log download api.
• Add reminder for UTC-0
• Add time range preview for slow log to download.

[CLAassistant]

All committers have signed the CLA.

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-04-26 08:11:30.409987131 +0000 UTC m=+334247.149890040: :ballot_box_with_check: agreed by shhdgit.

[shhdgit]

/merge

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[shhdgit]

/approve

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