[release-v2.4] [DOC] Revised Tune search performance doc (#3595)

* Revised Tune search performance doc

* Apply suggestions from code review

* Apply suggestions from code review

Co-authored-by: Suraj Nath <[email protected]>

* Apply suggestions from code review

Co-authored-by: Suraj Nath <[email protected]>

* Apply suggestions from code review

* Update docs/sources/tempo/operations/backend_search.md

* Update docs/sources/tempo/operations/backend_search.md

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Co-authored-by: Suraj Nath <[email protected]>
(cherry picked from commit 1c0eefc)

Co-authored-by: Kim Nylander <[email protected]>