feat(web): Improved search performance on unbounded searches

[brendan-kellam]

TLDR: This PR improves search performance for unbounded searches by bounding the TotalMaxMatchCount closely to MaxMatchDisplayCount. Comment contains the details:

// @note: Zoekt has several different ways to limit a given search. The two that
// we care about are `MaxMatchDisplayCount` and `TotalMaxMatchCount`:
// - `MaxMatchDisplayCount` truncates the number of matches AFTER performing
//   a search (specifically, after collating and sorting the results). The number of
//   results returned by the API will be less than or equal to this value.
//
// - `TotalMaxMatchCount` truncates the number of matches DURING a search. The results
//   returned by the API the API can be less than, equal to, or greater than this value.
//   Why greater? Because this value is compared _after_ a given shard has finished
//   being processed, the number of matches returned by the last shard may have exceeded
//   this value.
//
// Let's define two variables:
// - `actualMatchCount` : The number of matches that are returned by the API. This is
//   always less than or equal to `MaxMatchDisplayCount`.
// - `totalMatchCount` : The number of matches that zoekt found before it either
//   1) found all matches or 2) hit the `TotalMaxMatchCount` limit. This number is
//   not bounded and can be less than, equal to, or greater than both `TotalMaxMatchCount`
//   and `MaxMatchDisplayCount`.
//
//
// Our challenge is to determine whether or not the search returned all possible matches/
// (it was exaustive) or if it was truncated. By setting the `TotalMaxMatchCount` to
// `MaxMatchDisplayCount + 1`, we can determine which of these occurred by comparing
// `totalMatchCount` to `MaxMatchDisplayCount`.
//
// if (totalMatchCount ≤ actualMatchCount):
//     Search is EXHAUSTIVE (found all possible matches)
//     Proof: totalMatchCount ≤ MaxMatchDisplayCount < TotalMaxMatchCount
//         Therefore Zoekt stopped naturally, not due to limit
//     
// if (totalMatchCount > actualMatchCount):
//     Search is TRUNCATED (more matches exist)
//     Proof: totalMatchCount > MaxMatchDisplayCount + 1 = TotalMaxMatchCount
//         Therefore Zoekt hit the limit and stopped searching
//

This PR deprecates the following env vars:

• SHARD_MAX_MATCH_COUNT
• TOTAL_MAX_MATCH_COUNT
• ZOEKT_MAX_WALL_TIME_MS

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch bkellam/search_time_improvements

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